Bearings – Linear bearing – Recirculating
Reexamination Certificate
1999-10-12
2002-05-21
Marmor, Charles A (Department: 3681)
Bearings
Linear bearing
Recirculating
C384S044000
Reexamination Certificate
active
06390679
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a linear guide device used as a linear guide in a machine tool, an industrial machine and the like.
Conventionally, as a linear guide for use in a machine tool, an industrial machine and the like, there is known a linear guide device, that is, a linear guide bearing device
51
shown in FIG.
8
. The linear guide bearing device
51
shown in
FIG. 8
comprise a guide rail
53
extending in one direction and serving as a guide member, and a slider
54
disposed in such a manner that it is freely movable along the longitudinal direction of the guide rail
53
.
The guide rail
53
includes a plurality of rolling element rolling grooves
55
on the outer surface thereof in such a manner that they respectively extend in the longitudinal direction of the guide rail
53
. And, the slider
54
includes a slider main body
56
so formed as to have a U-shaped section, and two end caps
57
respectively mounted on the two end faces of the slider main body
56
; and, the slider
54
is disposed in such a manner that it strides the guide rail
53
.
The slider
54
includes a plurality of load rolling element rolling grooves
58
which respectively correspond to their associated rolling element rolling grooves
55
of the guide rail
53
. The rolling element rolling grooves
55
and the load rolling element rolling grooves
58
are respectively opposed to and combined with each other to thereby form their associated load rolling passages
61
.
The slider
54
further includes a plurality of rolling element return passages
59
which are respectively formed in the interior portion of the slider
54
and extend substantially parallel to their associated load rolling element rolling grooves
58
, and a plurality of curved passages
65
respectively connecting together the mutually associated load rolling passages
61
and rolling element return passages
59
.
The above-mentioned load rolling passages
61
, rolling element return passages
59
and curved passages
65
cooperate together in forming their associated rolling element circulation passages
66
. Within each of the rolling element circulation passages
66
, there are loaded a plurality of balls
60
serving as the rolling elements. The balls
60
are arranged in such a manner that they roll with a load within the load rolling passage
61
as well as they roll with no load within the curved passage
65
and rolling element return passage
59
. Such rolling motion of the balls
60
allows the slider
54
to be freely movable along the longitudinal direction of the guide rail
53
.
Also, over each set of the load rolling passage
61
and curved passage
65
of the slider
54
, there is disposed a crowning
70
serving as an expansion portion which is formed in direction where the load rolling element rolling groove
58
moves away from its associated rolling element rolling groove
55
. The reason why the crowning
70
is disposed is that it allows the balls
60
to circulate smoothly even if the balls
60
move into a load area such as the load rolling passage
61
from a no-load area such as the rolling element return passage
59
, curved passage
65
and the like.
Further, the slider
54
includes, in the inside portions of the end caps
57
that are disposed opposed to the guide rail
53
, tongue portions
67
each serving as a scooping portion (in other words, a take-up portion) which can be contacted with the balls
60
moving into the curved passage
65
from the load rolling passage
61
to thereby guide the balls
60
into the curved passage
65
.
In the above-mentioned conventional linear guide bearing device
51
, as shown in
FIG. 8
, in each crowning
70
, in some cases, between the tongue portion
67
formed in the curved passage
65
and a ball
60
a
serving as a load rolling element which belongs to the balls
60
rolling with a load within the load rolling passage
61
and is situated in the end portion of the load rolling passage
51
, there can exist an even number of balls
60
b
serving as no-load rolling elements which roll with no load. By the way, in
FIG. 8
, the balls
60
b
are present two in number.
At the then time, one of the two balls
60
b
serving as a no-load rolling element, which is situated on the right in FIG.
8
and is contacted with the tongue portion
67
, rolls along a direction of an arrow line M
2
shown in
FIG. 8
which is the opposite direction to the rotation direction thereof in which the ball
60
b
runs up onto the tongue portion
67
and moves into the curved passage
65
.
Due to this, the dynamical friction force of the linear guide bearing device
51
varies as in portions which are respectively enclosed by two-dot chained lines Qs shown in
FIG. 9 and
, actually, as the present dynamical friction force varies, the dynamical friction force of the ball
60
b
also increases, which raises an unfavorable problem.
By the way, in
FIG. 9
, the dynamical friction force of the linear guide bearing device
51
, which is obtained when the linear guide bearing device
51
is moved in one direction extending along an arrow line S
1
shown in
FIG. 8
, is shown as a positive dynamical friction force; and, on the other hand, the dynamical friction force, which is obtained when the linear guide bearing device
51
is moved in the other direction extending along an arrow line T
1
shown in
FIG. 8
which is the opposite direction to the arrow line S
1
direction, is shown as a negative dynamical friction force.
SUMMARY OF THE INVENTION
The present invention aims at eliminating the drawbacks found in the above-mentioned conventional linear guide bearing device. Accordingly, it is an object of the invention to provide a linear guide device which not only can reduce a dynamical friction force generated when moving a guide member but also can control variations in the dynamical friction force.
In solving the above problems and attaining the above object, according to the invention, there is provided a linear guide device comprising: a guide member including a plurality of rolling element rolling grooves respectively formed in the outer surface thereof; a slider disposed on the guide member in such a manner that it is free to move along the guide member, the slider including a plurality of load rolling element rolling grooves respectively opposed to and combined with the rolling element rolling grooves of the guide member and cooperating with the rolling element rolling grooves in forming their associated load rolling passages, and a plurality of curved passages respectively connected to the thus formed load rolling passages; and, a plurality of rolling elements loaded in each of the load rolling passages and curved passages, the rolling elements not only rolling with a load within their associated load rolling passages but also rolling with no load within their associated curved passages, wherein, in an area ranging over each set of the load rolling passage and curved passage, there is formed an expansion portion extending in a direction where the load rolling element rolling groove moves away from its associated rolling element rolling groove, the expansion portion being structured such that, between the load rolling element that belongs to the load rolling elements rolling with a load within the load rolling passages and is situated in the end portion of the load rolling passage and a rolling element take-up portion formed in each of the curved passages, there can be present an odd number of no-load rolling element (elements) rolling with no load.
In other words, according to the present linear guide device, there is formed the expansion portion in such a manner that, between each curved passage and the load rolling element that belongs to the load rolling elements rolling with a load within their associated load rolling passage and is situated in the end portion of the present load rolling passage, there can be present an odd number of no-load rolling element (elements).
The no-load rolling element, which is going to move into the curved passage
Ho Ha
Marmor Charles A
NSK Ltd.
Sughrue & Mion, PLLC
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