Antifriction bearing for longitudinal movements of a shaft

The arrangement according to the invention provides a sealing ring fastened to the end ring in a manner secure against removal by pulling or twisting. This sealing ring is provided with thickened extended arms and is fastened by snapping in the thickened arm sections behind an internal radial shoulder through openings in the flange of the end ring. The opening in the flange of the end ring may be economically manufactured, as by means of axial forms or cores, and without the need for additional radial cores, within the casting mold.

BACKGROUND OF THE INVENTION 
The present invention concerns a rolling linear shaft bearing wherein 
closed rows of rolling elements are distributed around the circumference 
of the bearing. 
Bearings of this type are provided with an outer housing having 
longitudinal sections distributed over the circumference of the housing 
bore, such sections bearing the loaded and unloaded raceways of each row 
of rolling elements. The bearing cage is located in the bore of the outer 
housing, the cage ends axially protruding with respect to the outer 
housing. The end ring is manufactured by casting, mounted one each on 
either end of the bearing cage, and an elastic sealing ring is fixed to 
each end ring. 
DESCRIPTION OF THE PRIOR ART 
In a conventional rolling bearing for longitudinal movements, the end rings 
include, in their bore, an annular slot containing a radially secured 
sealing ring, which laterally covers the bearing cage. See, for example 
U.S. Pat. No. 4,123,121. In such conventional rolling bearings the 
manufacture of the end rings is expensive because the annular slots of the 
end rings must be introduced into the bore of the end rings, either by 
means of complicated radial cores during the casting of the rings, or, 
after the casting, by an additional cutting-type machining. In addition, 
the sealing ring of the known rolling bearing cannot be easily fastened 
against twisting within the antifriction bearing. If there is significant 
thermal expansion of the end ring during operation, the sealing ring may 
loosen and may rotate on its own, which is undesirable due to the risk of 
wear. 
In applications with lateral lubricant supply, as well as when the sealing 
ring is replaced, there is no sealing ring at one or both ends of the 
bearing. In the case of bearings, the respective front side of the bearing 
cage is then uncovered, so that damage to the bearing cage by means of 
gripping or mounting tools is not excluded. 
If a conventional bearing is not equipped with sealing rings, the annular 
slot may form an undesirable radial cavity within the bore of the end 
ring, which cavity retains dirt and dust. Furthermore, the end rings of 
the friction bearing are then designed unnecessarily wide in an axial 
direction, which may constitute a disadvantage in case of a narrow 
mounting space. 
It is therefore the object of the invention to provide a rolling linear 
shaft bearing with a sealing ring which is secured against twisting within 
the bearing, in a simple manner. 
It is a further object of the invention to provide a bearing cage with 
protection against dirt contamination or damage, even then when one or 
both sealing rings are disassembled. It is another object of the invention 
to provide a linear rolling bearing of economic manufacture and simple 
assembly, as one compact structure unit. 
BRIEF DESCRIPTION OF THE INVENTION 
The arrangement according to the invention provides a sealing ring fastened 
to the end ring in a manner secure against removal by pulling or twisting. 
This sealing ring is provided with thickened extended arms and is fastened 
by snapping in the thickened arm sections behind an internal radial 
shoulder through openings in the flange of the end ring. The opening in 
the flange of the end ring may be economically manufactured, as by means 
of axial forms or cores, and without the need for additional radial cores, 
within the casting mold. No subsequent machining of the end ring, which 
would render manufacture more expensive, is required. Furthermore, the 
flange, which laterally covers the bearing cage, provides protection 
against the penetration of undesirable contamination within the 
antifriction bearing, as for example when the sealing rings are 
disassembled. Furthermore, the flange of the end rings ensures that the 
bearing cage is protected against shocks of mounting tools and the like, 
when the sealing rings are assembled or when the antifriction bearing is 
axially pressed onto its seat in the bore of a housing. In the assembly of 
the antifriction bearing or replacement of parts (substitution of seals), 
the sensitive sealing rings may be preassembled onto the pertinent end 
ring, at the factory, producing a sturdy structural unit together with the 
end ring. Therefore, the sealing rings are protected against damage upon 
the subsequent assembly of the antifriction bearing. 
In a further embodiment, traversing openings are provided in the end ring 
which is easily molded by means of pins running in the axial direction of 
an axial core used to form the casting mold. Alternatively, a simple 
snap-button type fastening of the arms in the end ring is employed. 
In accordance with a further embodiment the end ring and associated sealing 
ring are retained at the end of the bearing cage, secured against removal 
by either twisting or axial pulling, or both. 
In an additional embodiment, the sealing ring is fastened to the end ring 
which relatively low mounting forces, since the radial projection of each 
arm is pressed radially outward, in accordance with the elastic bending of 
the arm, when the arms are pressed into the opening of the end ring. 
In a further embodiment a simple fastening of the sealing ring to the end 
ring, with simultaneous security against twisting of the end ring on the 
bearing cage, is achieved by providing an indentation in the cage for a 
projection on the arm. 
In an additional embodiment, the arms of the sealing ring are located 
radially outward, by means of a radial recess in the ring so that the 
bearing cage can feature a relatively large outside diameter, even at its 
ends, for the purpose of accommodating the rolling elements. 
In a still further embodiment, the end rings are secured with an associated 
sealing ring on the respective end of the bearing cage, not only against 
twisting, but also against pulling off from the bearing cage, by a 
retaining catch on the sealing ring. 
Finally, a further embodiment provides for openings and recesses in the end 
ring produced in particularly economic fashion, by means of smooth, 
shoulderless pins, in the axial core of the casting mold for the end rings 
.

DETAILED DESCRIPTION OF THE INVENTION 
In FIGS. 1 and 2, 1 represents th external housing of a rolling bearing for 
longitudinal movements. In the bore of this external housing 1 there is 
located the bearing cage 2 with closed rolling-element rows 3, which are 
distributed over the bearing circumference. In the bore of external 
housing 1 there are located longitudinal sections, distributed over the 
circumference, which bear the loaded and unloaded raceways of each 
rolling-element row 3. 
Bearing cage 2 has two ends 4 which protrude axially in relation to 
external housing 1. On each end 4 of bearing cage 2 there is mounted an 
end ring 5, which is manufactured by casting, e.g., injection-molding, and 
may consist of plastic. 
This end ring 5 has a flange 6, running radially inward, that covers 
bearing cage 2 on the front side, which flange forms an external front 
side 7 on end ring 5. Axially running openings 8 are provided on the 
circumference of this front side 7. 
As can be seen in particular in FIGS. 3 and 4, this opening 8 extends 
through flange 6 and ends without a shoulder in an adjacent radial recess 
9, in bore surface 10 of end ring 5, which surface is located on end 4 of 
bearing cage 2. The cross-section of opening 8 is constant along the depth 
of the opening. The cross-section is larger in a circumferential direction 
than in a radial direction (FIG. 4). 
On each of the external front-sides 7 of the two end-rings 5 there is 
fastened an elastic sealing ring 11. This sealing ring 11, on the side 
thereof facing the front-side 7, is provided with arms 12 extending in an 
axial direction, with a projection 13, pointing radially inwards, formed 
as a thickening at the respective ends. Each of the arms 12 of the sealing 
ring 11 engages in an associated opening 8, in a manner such that the 
projection 13 snaps behind a radial shoulder of end ring 5. This shoulder 
is formed, in the present case, by the stepwise front surface 23 of flange 
6, which points inward in an axial direction. The cross-section of arms 12 
is matched on a positive manner with the cross-section of opening 8, 
whereby a small radial clearance is provided between each arm 12 and the 
radial external wall of opening 8 (FIG. 4). 
When sealing ring 11 is fastened to end ring 5, the latter is placed 
axially against end ring 5, so that its arms 12 can be pressed axially 
into the associated opening 8. In so doing, the arms 12 are somewhat bent 
radially outward, as a result of contact by the projection 13 with the 
wall of opening 8, the arms 12 being flexurally stretched in an elastic 
manner. At the end of the pressing passage of arms 12 into opening 8, 
sealing ring 11 comes in contact with the front surface 7 of end ring 5. 
At the same time the arm 12, bearing projection 13, enters recess 9, 
projection 13 snaps behind front surface 23 of flange 6, and thus axially 
fixes sealing ring 11 to end ring 5. Each arm 12 furthermore touches the 
radial inner wall of opening 8, under elastic pre-tension, so that sealing 
ring 11 is held against end ring 5 in a manner that is free of play, 
centered, and secure against twisting. The end ring 5, together with the 
sealing ring 11, forms a rugged preassembled structural unit, which may be 
mounted and dismounted without risk of damaging the sensitive sealing ring 
11. 
A retaining catch 14 that protrudes radially over the perimeter surface of 
end ring 4 of bearing cage 2 (FIG. 5) engages recess 9 in a positive 
manner, so that end ring 5 is secured on bearing cage 2 in an axial 
direction and against twisting. When end ring 5 is mounted, it is pushed 
with sealing ring 11 on end 4 of bearing cage 2, in an axial direction so 
that end ring 5 is pushed with its bore 10 over retaining catches 14 and 
is somewhat spread, elastically. In so doing, the internal front-surface 
of end ring 5 finally comes into contact with external housing 1, and 
retaining catch 14 snaps into recess 9 in the bore of end ring 5. In so 
doing, both the arm 12 of sealing ring 11 that carries projection 13, and 
the radially protruding retaining catch 14 of bearing cage 2, engage in a 
positive manner in recess 9. 
On the internal front-side of end ring 5, radially running indentations 15 
are provided, for the supply of lubricant via channels 16, into the inside 
of the bearing. 
In FIG. 6 there is indicated a partial longitudinal section of a modified 
rolling bearing, which is constructed in a manner similar to the rolling 
bearing shown in FIGS. 1 to 5, with corresponding elements of different 
shape being primed. Each arm 12' of sealing ring 11' again has a 
projection 13' facing radially inward, as a thickening. This projection, 
again as in the previously described example of implementation, engages 
through the opening 8 in the recess 9 that follows it without a shoulder. 
However, here there is a radial cavity 17 machined into the perimeter 
surface of end 4 of bearing cage 2', which cavity features a lateral wall 
18 that serves as a radial shoulder, and faces axially inward. Projection 
13' of each arm 12', in this embodiment, thus snaps behind lateral wall 
18, so that sealing ring 11' and end ring 5' are fastened to bearing cage 
2', by means of arms 12', against axial removal as well as against 
twisting. In this fashion, no retaining catches for securing end ring 5' 
on the bearing cage 2' need be provided on the perimeter surface of end 4 
of bearing cage 2'. 
FIG. 7 shows a partial longitudinal section of a further modified bearing, 
which is again designed in a manner similar to that described in FIGS. 1 
to 5, corresponding elements of different shape being double primed. 
Again, the thickening on the end side is provided in the form of a 
projection 13", pointing radially inward, on each arm 12" of sealing ring 
11". This projection 13" is also arranged so as to snap behind a shoulder 
of end ring 5", which shoulder is formed by the plane front-surface 23 of 
flange 6", which surface points axially inward. However, here projection 
13" engages radially in an indentation 19, on the end side of bearing cage 
12", in a fashion such that here not only is sealing ring 11" secured 
against twisting in end ring 5", but also end ring 5" is secured against 
twisting on bearing cage 12". 
FIGS. 8 and 9 indicate, in partial cross-sectional views, a further 
modified bearing, with elements of different shape than those 
corresponding to the embodiment of FIGS. 1-5 being triple primed, 
featuring a sealing ring 11'" with arms 12'", which arms feature at their 
ends a snap-button type thickening 20. The shoulder is formed by the 
lateral wall 21, pointing axially inwards, of a groove that is machined 
into the circumference of opening 8'". The sealing ring 11'" here consists 
of an elastic compressible material, such as plastic. Upon mounting and 
axially pressing-on sealing ring 11'", arms 12'" are pushed into opening 
8'". In so doing, the thickened parts 20 are first pushed together in an 
elastic manner, until these thickened parts snap into groove 22, and thus 
secure sealing ring 11'" against end ring 5'", in a twist-proof fashion. 
By the same token, the end ring 5'" with built-in sealing ring 11'" may be 
gripped and pressed axially, by means of appropriate tools (not shown), 
whenever sealing ring 11'" must be disassembled or replaced. 
The examples of implementation described above, for a linear rolling 
bearing, may be widely modified, within the framework of the concept of 
the invention. In particular, the cross-section of the openings in the end 
ring and the cross-section of the arms of the sealing means accommodated 
into these openings, may feature, depending on the nature of their stress 
and/or the construction of the antifriction bearing, an essentially 
rectangular or circular form. This form may be easily changed, by 
replacing the mold pins used in the axial of a casting mold for the end 
ring, without causing major tooling costs. 
Furthermore, the sealing ring may protrude radially over the perimeter 
surface of the external housing and of the end ring, and thus may form an 
abutting shoulder for the axial fixation of the bearing in a housing or 
similar device. Other embodiments within the spirit and scope of the 
invention will be apparent to those skilled in the art.