Moulded roller bearings and retainer cage and method of assembling drawer slides

A moulded roller bearing cage assembly for use for drawers and cabinets replaces standard metallic bearing cages and balls. The bearing cage, its rollers detachably fixed within the apertures, is loaded between the flanges of the channels on the standard two or three part drawer slide. The rollers before and during assembly are fixed at their ends integrally with the cage to allow for easy installation. Once the rollers come in contact with the raceways of the installation the detachable links are broken allowing the rollers to be free to rotate. The rollers and cages can be moulded in any configuration to allow for different channel and raceway shapes.

FIELD OF INVENTION 
This invention relates to drawers and cabinets and particularly sliding 
mechanisms for drawers and cabinets. More particularly this invention 
relates to bearings and cages such as ball retainers for the slides of 
drawers and cabinets. 
BACKGROUND OF THE INVENTION 
In order to reduce friction and to be able to withstand heavy loading, 
drawer slides for such applications as file cabinets employ bearings to 
reduce wear. Two types of slides are commonly used in file cabinets. 
One type of slide which employs two or three channels can be taken apart in 
order that the outer slide can be attached to the cabinet wall and the 
inner slide attached to the side of the drawer or vice versa. In such 
applications, a bearing cage retainer is used in conjunction with metal 
ball bearings. The former retains the balls between the retainer and the 
inner side of the flange. Clearly the apertures in the bearing retainer 
have a smaller circumference than that of the balls. 
In other applications where it is not necessary to take apart the drawer 
slide after assembly for later installation in the cabinet a second type 
of drawer slide is used. In this second type of drawer slide, different 
retainers can be used. All of these retainers have in common apertures in 
the retainer which are larger than the diameter of the balls. The balls 
are prevented from laterally displacing by the two adjacent flanges of the 
channels. Since these channels are not disassembled during installation on 
the drawer and cabinet the second type of retainer can be used. 
One model of this second type of retainer is manufactured from plastic in 
the form of a channel having upturned side flanges much the same as the 
metal channel slides used to form the slide itself. Apertures are made 
along both flanges and balls are inserted during assembly. 
Another model of this second type of retainer in use, employs a 
longitudinal plastic bar which fits between the flanges of the outer and 
intermediate or intermediate and inner channels. It has two or more 
apertures in which metal balls are inserted (often by hand) during 
assembly. 
It is the second type of slides, that is to say those which are not 
disassembled for installation, to which the present invention pertains. 
All of the aforementioned drawer slides have certain problems. Firstly the 
retainers are expensive. Secondly they take up additional valuable space 
in the drawer cabinet application. In addition the metal retainers are 
cumbersome to fabricate, and the slide assembly process is time consuming. 
Retainers must be placed in the channels by hand and then balls loaded 
pneumatically through ball bearing feed lines. Human error often occurs or 
the machine malfunctions resulting in a large number of balls escaping 
around the work area and causing a safety hazard. Another problem exists 
because of the shape of the metal balls. Because of the spherical shape 
all of the mating raceways of the flanges of the channels must be circular 
in configuration. When a three part slide is used and two sets of friction 
reducing retainers are used significant waste in materials and space is 
encountered. 
SUMMARY OF THE INVENTION 
The present invention seeks to overcome these problems by providing a 
unique moulded bearing cage with rollers formed from plastics. 
It is an object of the present invention to facilitate faster, easier and 
less expensive assembly while maintaining the quality of the present 
friction reducing slides. It is a further object of the invention to 
provide for an inexpensive bearing cage at a fraction of the cost of those 
presently available. And it is a further object of this invention to 
reduce the loss of balls or rollers during assembly by providing a bearing 
cage with rollers connected thereto by a detachable link which connects 
the rollers to the cage. It is a further object of this invention to 
provide for bearing cages and rollers in varying configurations which 
allow for different configurations of flanges on slide channels, thereby 
reducing the amount of material required and, shortening the pressing or 
stamping time required to form such channels. 
Therefore this invention seeks to provide a moulded roller bearing cage 
assembly for use with slides for drawers and cabinets comprising a 
plurality of rollers and a cage having a plurality of apertures; wherein 
the maximum diameter of said rollers exceeds the maximum width of said 
cage; said rollers being positioned in said apertures and integral with 
said cage and being connected to said cage at their ends solely through 
narrow frangible links; said frangible links serving to maintain said 
rollers in position in their apertures until and during the time of 
installation and thereafter being breakable by engagement with raceway 
surfaces in the installation to enable rotation. 
This invention also seeks to provide a method for making drawer slides 
having at least two channels comprising the steps of (1) positioning a 
first channel member on the work station, said channel having right angled 
side flanges; (2) positioning at least one roller bearing cage assembly as 
claimed in claim 1 adjacent the inside of each side flange; (3) inserting 
a second narrower channel member having right angled side flanges within 
said first channel member, such that said roller bearing cage assembly is 
securely positioned between the inside of said flange of said first 
channel and the outside of said flange of said second channel, thereby 
causing said frangible links to sever and allowing said rollers to be free 
for rotation; (4) repeating steps (2) and (3) if a third channel is 
necessary. 
In a preferred embodiment the bearing cage assemblies are manufactured in a 
two sided mould from new recently discovered thermal plastics. The bearing 
cage assemblies can be made in a group by using a daisy chain method. The 
cages are generally longitudinal in shape and of the same approximate 
height as the flanges of a slide channel used in a two or three part 
slide. The number of apertures and rollers in the bearing cage assembly 
can be varied depending upon the particular application. Typically a 
bearing cage could be anywhere from two to eight inches long and contain 
anywhere from six to twenty-four rollers. The cross section of the cage 
and rollers is dependent upon the configuration of the mating adjacent 
flanges of the two slide channels. 
For example the configuration could be diamond shaped wherein the rollers 
are considerably greater in diameter at their mid-point than at their 
respective ends. Other configurations however are equally useful. For 
example, if the two adjacent flanges of the two slides tend to come closer 
together at their mid-height a roller cage assembly can be moulded to have 
each end of the rollers larger in diameter than the mid-portion of the 
rollers. 
Generally the assembly is moulded having the rollers attached at each of 
the their ends on the longitudinal axis to the top and bottom of the cage. 
The cages are moulded to have apertures which are greater in height and 
width than the rollers. The greatest thickness or greatest diameter of the 
rollers is always moulded larger than the maximum thickness of the cage so 
that it is the rollers which come in contact with the raceways rather than 
the cage. 
It should be noted that the roller bearing cage assembly is not restricted 
to use with two or three part slide channels for cabinets. Because of the 
versatility of the unique roller bearing assembly of the present invention 
it can be used in any type of application where a drawer and cabinet is 
used. For example it could be used on kitchen drawers to provide an 
inexpensive method of reducing friction and wear. Because of the 
versatility of the moulding process the size, length, height and thickness 
of the cages and rollers can be varied to any application. 
In the preferred embodiment the bearing cage assemblies contain a number of 
apertures in each of which a roller bearing is located and connected at 
its axis to the top and bottom of the cage. The cage assemblies are 
moulded on a daisy chain and are fed on a roller toward the work station. 
An outer slide or flange is placed on the work station and a cage assembly 
is lowered downward inside and adjacent to the flange on the outer side 
channel. Thereafter an intermediate or inner slide is slid therein such 
that the inside portion of the flange of the outer channel is on one side 
of the rollers and the outside portion of the flange of the inner or 
intermediate channel is adjacent the opposite side of the rollers thereby 
holding the cage assembly in position. When the outside edges of the 
rollers come in contact with the flange raceways the frangible links 
attaching the rollers to the cage are broken thereby leaving the rollers 
for free rotation. The two flanges of the channels prevent the rollers 
from laterally displacing, and the side, upper and lower limits of the 
aperture of the bearing cage prevent up and down and longitudinal 
displacement of the rollers. Limiting stops can be placed between the 
flanges so that the roller cage does not stray from between the two 
flanges in the longitudinal direction.

DETAILED DESCRIPTION OF THE DRAWINGS 
FIG. 1 illustrates a prior art three channel drawer slide. In cross-section 
there is an outer channel 1, an intermediate channel 2, and an inner 
channel 3. The channels have upturned or downturned flanges depending upon 
the adjacent mating flange. For example, the outer channel 1 has an 
upturned flange 8, and intermediate channel 2 has a more complicated 
configuration with an upturned flange 9 and a downturned flange 10. Inner 
channel 3 has a curvilinear downturned flange 11. As one can see, the 
flanges 8, 9, 10 and 11 must be formed in a manner such that their 
raceways will accommodate the standard balls 6 and 7. The balls 6 and 7 
are retained in place by standard bearing cages 4 and 5 respectively. The 
balls reduce friction between the outer slide 1, the intermediate slide 2, 
and the inner slide 3. 
FIG. 2 is a perspective view cf a portion of a standard bearing cage 12 
which is similar to that used in the prior art slide shown in FIG. 1 and 
noted as numbers 4 and 5. It has a base portion 14, upturned side flanges 
13 with a plurality of holes 15 of slightly greater diameter than the 
balls 16. Once the retainers have been placed in their respective channels 
during assembly, balls are introduced and the flanges of adjacent channels 
hold the balls in place with the help of the bearing cage 12. 
With this type of cage 12, the assembled drawer slide cannot be taken apart 
for installation in a drawer and cabinet, as the removal of any one of the 
three channels will result in the balls falling from place. The assembly 
of a three part slide using the channels, balls and retainers shown in 
FIGS. 1 and 2 is time consuming and often results in errors as the balls 
drop from their position before the two adjacent flanges of adjacent 
channels are in place. 
FIG. 3 illustrates an embodiment of the present invention in perspective 
view. Number 17 shows three moulded roller bearing cage assemblies 18 
attached by a detachable daisy chain 19. The individual assemblies 18 are 
moulded in a two part mould from thermal plastics. Roller bearing cage 
assembly 18 is comprised of a cage 22 having a top 20 and a bottom 21. 
Cage 22 has a number of apertures 23 each of which is adapted to receive 
roller bearing 24. During moulding and prior to assembly of a slide, the 
roller bearings 24 are connected and held in place in the apertures of the 
cage by means of frangible links 25. Generally these links are located on 
the longitudinal axes of the rollers at either end. However, it would be 
possible to attach the rollers at some other point by frangible links. One 
can visualize by examination of FIG. 3 that prior to assembly, the rollers 
24 will not move from the retaining cage 18. 
FIG. 4 is an enlarged side view of the portion of a roller bearing cage 
assembly 18. In the embodiment of the invention shown in FIGS. 3 and 4 a 
diamond shaped roller with a wide mid-section is used. The roller bearing 
24 is however smaller in circumference than aperture 23 in the cage. One 
also views the frangible links 25 joining the roller bearing 24 to the top 
20 and bottom 21 of the cage. 
FIG. 5, is an end view of a bearing cage assembly 18 One notes that the 
diameter of the roller bearing 24 at its mid point is wider than the 
greatest width of the cage 22. This is necessary so that the sides of the 
roller, rather than the non-rotational sides of the cage come in contact 
with the raceways of the channel flanges. 
In FIG. 6, one views an embodiment of the invention as shown in FIGS. 3, 4 
and 5, in place in a cross-sectional view of a three channel drawer slide. 
The drawer slide has an outer channel 26, an intermediate channel 27 and 
an inner channel 28. The side flanges of channels 26, 27 and 28 are 
respectively 31, 30 and 29. The flanges are formed in such a manner as to 
receive one diamond shaped roller bearing assembly between the flanges 
intermediate channel 27 and the outer channel 26, and a second roller 
bearing assembly between the flanges of the intermediate channel 27 and 
the inner channel 28. On the left side of FIG. 6 the whole cross section 
of the cage 22 is shown, but on the right side a portion of the cage 22 is 
removed exposing the roller 24. Also in FIG. 6 the frangible links 25 are 
shown. However, in reality the links are broken when the 3 channels are 
assembled. One notes in FIG. 6 that the width of the roller 24 at its mid 
point is wider than that of the cage 22. Thus, the sides of the rollers 
turn within the raceways created by the flanges 31 and 30 and 30 and 29. 
To assemble the three channel slide as shown in FIG. 6, the outer channel 
26 is placed on the work place and two strings of roller bearing cage 
assemblies 17 on daisy chain 19 are fed downwards from an upper machine. 
One assembly 18 is fitted on the inside of flange 31 on one side of the 
channel and another is placed inside flange 31 on the other side of the 
channel. The intermediate channel 27 is then pushed within channel 26 from 
one end into place. The daisy chain link 19 is then broken. At the same 
time as the raceways of channel 27 i.e. flange 30 come into contact with 
the roller bearings 24 thereby exerting pressure against the inside of 
flange 31, the frangible links 25 are broken. When the two channels are in 
place, the rollers 24 are prohibited from longitudinal, vertical and 
transverse movement (but are still free for rotation) from their positions 
in the cage assembly 18, even though the frangible links are broken. 
FIGS. 7, 8 and 9 show alternative embodiments of the invention all 
positioned within three-part channel slides of varying configurations. 
These three cross-sectional figures illustrate the versatility of the 
present invention. Unlike the prior art, the flanges of the channels need 
not maintain the configuration necessary to keep a ball but can be formed 
in any manner which is suitable and the moulded roller bearing cage 
assembly of the present invention can be adapted to fit within these 
varying configurations of flanges. In addition the "straight line effect" 
of the rollers in FIG. 9 reduces wear and stress. 
In FIG. 7, one sees in cross-section a roller bearing cage assembly which 
is in a sense the reverse of that shown in FIG. 6. The roller bearings 24a 
are shaped like an hour glass having a mid point of minimum diameter and 
each end of maximum diameter. The bearings are moulded in similar cages as 
that shown in the first embodiment with the exception that the 
cross-section of the cage has a cross-section which is almost of a 
constant width. In order for the roller to turn within the raceways of the 
flanges of channels 26a, 27a, and 28a, the diameter of the bearing 24a is 
larger than cage 22a throughout. This allows the rollers 24a to turn 
against the raceways of the channels namely flanges 29a and 30a, and 30a 
and 31a, respectively. 
The assembly of a three channel slide as shown in FIG. 7 is similar to that 
of FIG. 6 and similarly the frangible links 25 are broken when channel 27a 
is fitted within 26a and again when channel 28a is fitted within channel 
27a. One also notes that the top and the bottom of the cage assembly 20a 
and 21a respectively are in similar positions to that shown in FIG. 6. 
In FIG. 8 one sees a third embodiment of the invention. The roller 24b has 
a similar shape to roller 24a except that the side configuration is 
curvilinear rather than straight shaped, in cross-section. The drawer 
slide shown in the transverse cross-section view of FIG. 8 is a 
combination of an embodiment of the present invention along with a prior 
art embodiment using a retainer 4 with balls 6. Channels 26b, 27b and 28b 
have flanges 31b, 30b and 29b respectively configured to adapt to the 
different roller and balls used. Again on assembly the frangible links 25 
which attach the rollers 24b to the cage 22b of the bearing cage assembly 
18 are broken when the channel 28b is fitted within channel 27b during 
assembly. 
Finally, FIG. 9 is a transverse cross-section of a three channel drawer 
slide which employs roller bearings of similar configurations as shown in 
FIG. 6 namely roller type 24 along with a roller type 24a as shown in FIG. 
7. Roller type 24 is used between flange 31 of outer channel 26 and flange 
30 of intermediate channel 27. Subsequently, roller type 24a is used 
between flange 30 of intermediate channel 27 and flange 29c of inner 
channel 28c. 
In conclusion, one can understand that the present invention is not 
restricted to the particular embodiments described herein but covers any 
type of drawer slide and cabinet arrangement in which rollers which are 
moulded together with the cage assembly from thermal plastics, and are 
connected to the said assembly with frangible links. Furthermore, the 
invention is not restricted to three or even two part slides but can be 
used in any drawer and cabinet where lower friction is desirable.