Roller construction for paper feeding

A paper feeding roller construction including a core of foamed cellular resilient material which has a shore hardness which is not measurable to thereby provide extremely easy compressibility, and an annular skin of a relatively hard elastic material on the core for providing toughness and abrasion-resistance, with the annular skin being coated onto the core so as to retain the cellular structure thereof on its surface to provide air pockets.

BACKGROUND OF THE INVENTION 
The present invention relates to an improved roller construction for 
feeding paper in various types of machines, such as copiers, calculators, 
printers, computers and wherever else paper feeding functions are 
required. 
By way of background, in the past relatively hard rubber rollers were 
utilized for paper feeding functions in various types of machines. These 
rollers were subject to certain shortcomings. In this respect, the rollers 
were relatively expensive to fabricate in that precision cutting and 
finishing procedures were required to make certain that the rollers were 
not out-of-round, as this could cause skewing of the paper being fed, or 
could cause extremely high pressure points on the paper, which could 
result in the tearing thereof. In addition, because of the relative 
incompressibility and inflexibility of prior art rollers, the surfaces 
thereof became glazed because of the retention of paper particles and the 
polishing action resulting in slippage between the rollers and the paper. 
This in turn resulted in defective paper feeding after a period of use, 
which in turn resulted in the necessity to either refurbish or replace the 
rollers. It is with the overcoming of the foregoing deficiencies of prior 
relatively hard paper feeding rollers that the present invention is 
concerned. 
SUMMARY OF THE INVENTION 
It is accordingly one important object of the present invention to provide 
an improved paper feeding roller which is extremely soft so that it can 
compress and flex to accommodate itself to the surface of the paper being 
fed even though it may not be perfectly cylindrical, thereby obviating the 
expense required to make rollers perfectly cylindrical. 
Another object of the invention is to provide an improved paper feeding 
roller which is not only soft so that it can accommodate itself to the 
surface of paper being fed, but which also has a relatively tough 
abrasion-resistant skin so that it will provide high resistance to wear. 
A further object of the present invention is to provide an improved paper 
feeding roller having a cellular structure on the outer surface thereof 
which provides the advantages of a good tread for gripping paper, and 
which, in combination with the flexibility and compressibility of the 
roller, provides a self-cleaning action to flick foreign particles from 
the surface of the roller, thereby obviating the glazing which results 
from their retention. 
Yet another object of the present invention is to provide an improved paper 
feeding roller which will provide a good paper feeding action when the 
paper can be moved but which, because of its easy compressibility, will be 
able to rotate while in contact with the paper without feeding it, and 
further, because of its self-cleaning action, will not become glazed. 
Other objects and attendant advantages of the present invention will 
readily be perceived hereafter. 
The present invention relates to a paper feeding roller construction 
comprising a core of extremely soft resilient material and an annular skin 
of relatively hard flexible material formed integrally with said core. 
Preferably the core is fabricated from foamed cellular resilient material, 
with the annular skin being coated onto the core so that the surface 
thereof includes depressions formed by the contour of a cellular 
structure. The core is also preferably open cell foamed resilient material 
which interlocks with the annular skin. The various aspects of the present 
invention will be more fully understood when the following portions of the 
specification are read in conjunction with the accompanying drawings 
wherein:

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The improved roller 10 includes a core or body 11 of foamed cellular 
elastic material which has been cut to have a central shaft receiving 
opening 12 and an outer cylindrical surface 13. While the core 11 is 
preferably made of polyurethane foam, it can also be fabricated of rubber 
spronge, esters, or ethers, or any other plastic material having elastic 
characteristics which can be made into a cellular foam. The cell structure 
may be open or closed, that is, the cells of body 11 may be in 
communication with each other or may be isolated from each other by the 
matrix of material. However, open cell foam is preferred because this 
characteristic will enable it to soak up the solution which is applied to 
it as an outer skin 14, as described hereafter. One of the main criteria 
of body 11 is that it should be so soft that it has substantially a zero 
Durometer reading, or it should at least be very soft. The cellular foam 
may have any desired density range which will give the foregoing 
characteristic, and such range may be anywhere between 1.2 pounds per 
cubic foot to 18 pounds per cubic foot. Under certain circumstances it may 
be possible to use a core or body 11 which is solid and not cellular, but 
such a core would not have the softness of a cellular structure, the 
softness of which depends on the combined elasticity of the matrix with 
air bubbles therein. 
An annular skin 14 is applied to body 11. As can be seen from FIG. 9, one 
way of applying skin 14 is by a roller coating action wherein a roller 15 
picks up liquid coating material 16 from tray 17 and carries it to doctor 
knife 19 which is spaced from roller 15 a predetermined distance to leave 
only a certain thickness of material 20 on roller 15 which is transferred 
to roller body 11. By this process the thickness of skin 14 can be 
controlled. Skin 14 is preferably a polyurethane polymer which can be 
applied to a thickness of anywhere between 0.005 inches to 3/32 of an inch 
or greater. The roller coating process provides a very even coating to 
roller body 11, thereby obviating any necessity for any trimming of the 
completed roller. A suitable polyurethane polymer which has been used is 
known under the trademark TRANCO and it has an identification number of 
MC-245. It will be appreciated that an extremely stable and solid roller 
10 is produced by the foregoing process in view of the fact that the 
solvent for skin 14 is also a solvent for body 11 so that the application 
of the solvent-containing coating to the outer surface of body 11 causes 
excellent adhesion between the core and the skin. As noted above, open 
celled polyurethane foam is preferred for core 11 because the coating will 
penetrate the outer annular portion of the core 11 and the skin 14 will 
become mechanically bonded to and interlocked with the fibers of the core. 
It will be appreciated that the skin 14 may be applied by methods other 
than roll coating, such as by spray coating or in any other suitable 
manner which will provide the desired skin structure on the surface of the 
roller as described hereafter. The skin is put on as a liquid and it 
hardens after application. No curing or subsequent fabricating processes 
are necessary. It will also be appreciated that the skin may have any 
desired hardness characteristic, or can be applied to any desired 
thickness, or it may have any desired coefficient of friction, or any 
desired elasticity. The hardness and stiffness of the rollers can be 
controlled by suitable selection of the thickness and hardness of the skin 
14. In addition, it may be any suitable material other than polyurethane 
which can be applied to the core 11 and which will adhere thereto. 
The basic characteristics of improved roller 10 are that it is extremely 
soft so that it can flex, as described hereafter, and it also possesses 
excellent abrasion-resistance because of the tough skin 14. The softness 
of core 11 permits the dimensioning and concentricity of the roller 10 to 
be inexact, and it will still provide good paper feeding. 
In FIG. 5 a roller 10 is shown which is not exactly cylindrical, that is, 
it has been fabricated out-of-round in the form of a truncated cone. 
Roller 10 is mounted on shaft 21 which extends through bore 12. Roller 10 
bears against a sheet of paper 22 which is supported on planar surface 22. 
Notwithstanding the uncylindrical shape of roller 10, the surface 24 of 
the roller which bears against paper 22 is in good full-face contact with 
the paper because the softness of the core 11 of roller 10 permits the 
roller to flex from its normal dotted-line configuration and bulge at 25 
to thereby permit the desired contact with paper 22. Because of the 
softness, there will be no skewing of the paper. An action of this type is 
impossible with a harder roller, which would only engage the paper with a 
portion of its surface and not across the entire width thereof, as shown 
in FIG. 5. 
In FIG. 6 there is shown a roller 10 mounted off-center on a shaft 26. The 
broken lines show the roller in its unstressed condition. The bore 12 is 
off-center so that radius a is smaller than radius b. However, the surface 
of the paper 27 being fed is only radius a distance away from shaft 26. 
Therefore, because of the softness of the core of roller 10, it can 
compress to assume the solid-line shape shown in FIG. 6, when the portion 
of radius b engages the paper. In this respect, the sides will bulge at 29 
but the amount of pressure between the roller 10 and the surface of the 
paper even when the portion of radius b is engaging it will be 
substantially the same as when the portion of radius a is engaging it, and 
this phenomenon is due to the softness of the core material 11. 
The foregoing softness characteristics of the rollers, as described 
relative to FIGS. 5 and 6, can be all the more appreciated when it is 
considered that a hard rubber roll, of the type heretofore used, needs 
precise dimensions in both its diameter and concentricity to make it 
practical, that is, to give it a uniform feeding characteristic. If the 
prior art roller was not precisely dimensioned and concentric, it would 
have produced erratic feeding or tearing, that is, it might have borne too 
hard in certain locations, or it might have missed the paper. As noted 
above, the improved roller 10 of the present invention is not subject to 
the foregoing shortcomings. In addition, the precision required for 
fabricating prior art hard rubber rolls caused them to be relatively 
expensive. However, the flexibility and adaptability of the improved 
rollers of the present invention permits a greater manufacturing tolerance 
and therefore permits them to be fabricated at a lower cost, while still 
providing excellent operational characteristics. 
The precision ground relatively hard rubber rolls of the prior art were 
applied against the paper being fed with a relatively light pressure. 
Under certain circumstances this caused slippage between the paper and the 
rollers. This in turn caused glazing of the surface of the rollers because 
of the abrasive characteristics of the paper, which, in turn, caused the 
rollers to lose their feeding ability. The feeding ability was also 
reduced because the rollers picked up proper fibers which functioned as a 
lubricant. In contrast to the foregoing, the improved rollers of the 
present invention can be pressed against the paper being fed with 
sufficient force so that the surface of the roller contacting the paper is 
in a relatively large area of contact with the paper. In other words, the 
"flat" of the roller is relatively large compared with the amount of 
surface of a harder rubber roller in contact with the paper. Stated 
otherwise, the improved roller of the present invention gives a 
rectangular area of good contact with the paper being fed, whereas the 
hard rollers of the prior art maintained substantially only line contact 
with the paper. Thus, the improved roller 10 of the present invention is 
capable of providing precise paper feeding because it maintains a 
relatively large surface of contact with the paper without subjecting the 
paper to excessive roller pressure. 
The improved roller 10 produces improved feeding characteristics because 
the surface 30 of skin 14 is essentially porous. In this respect, because 
of the manner in which the skin 14 is applied, as described above relative 
to FIG. 9, the coating follows the contour of the cellular structure. The 
cellular structure is visible from the surface of the roller, as depicted 
by FIGS. 3 and 4. Thus, a rough surface is provided which is in the nature 
of a tread so that there can be good engagement of the paper for feeding 
purposes. In other words, the surface of skin 14 will have hills and 
valleys which essentially follow the contour of the surface of core 11. 
This is generally the case when the thickness of skin 14 is below a 
predetermined value. 
The foregoing structure of skin 14 provides a plurality of advantages. One 
of these advantages is a self-cleaning action. In this respect, for 
example, in FIG. 8 a sheet of paper 31 is being fed along surface 32. 
Roller 10 bears against paper 31 in the zone X. During this bearing 
action, particles of paper may enter the depressions in skin 14. Also, it 
is to be noted that at this time roller 10, when operating in zone X, has 
a radius of substantially r because it is forced to a flattened condition 
in this area. However, after the roller 10 leaves paper 31, it expands to 
its normal larger radius R. It is believed that the expansion of the size 
of roller 10 from radius r to radius R causes a flicking action which 
flicks off particles of paper 33, and thus roller 10 possesses a 
self-cleaning action. It is believed that the flicking action is aided by 
the fact that there is a certain amount of air in the surface pores which 
acts as a lubricant and as a barrier for preventing foreign paper 
particles from adhering to the surface of skin 14. At this point it is to 
be noted that any desired concentration of pores can be used to obtain the 
foregoing action, and such concentration, or pattern, may be anywhere 
between 10 pores per linear inch to 100 pores per linear inch, measured 
along the circumference of the roller. For certain applications it may be 
desirable to depart from the foregoing parameters, depending on the size 
of the rollers and the purposes for which they are being used. At this 
present time it might be mentioned that the rollers described heretofore 
have a diameter of between 1/2 inch and about 2 inches. However, it will 
be appreciated that for rollers having greater diameters, it may be 
desirable to have less pores per linear inch than the 10 pores per linear 
inch mentioned above. 
Another characteristic of the porous surface of a roller such as 10 is that 
the cells on the surface of the rollers will accept air and therefore 
there will be no "planing" action, that is, an action where the roller 
runs on a layer of air between the surface of the roller and the paper 
being fed. In other words, as noted above, it is believed that the 
cellular surface structure of the roller, by accepting air, obviates 
planing. At this point it is to be noted that there are certain times that 
the roller 10 must rotate relative to the paper while the paper is being 
held. Under these circumstances it is believed that the ability of the 
cellular structure to receive air produces an air cushion which acts 
somewhat in the nature of a lubricant to permit slippage. 
Thus, there are two somewhat contradictory actions produced by the outer 
cellular structure, that is, (1) the trapping of air in the cells prevents 
"planing" when the paper is being fed, and (2) the cellular structure, by 
accepting air, permits relative slippage between the roller and the paper 
when the latter is being held because of the fact that the air pockets act 
as a lubricant. Furthermore, the softness of the core 11 permits the 
roller 10 to yield when the paper is being held so that there can be 
slippage without deleterious effects either resulting in the tearing of 
the paper or the ruining of the roller by glazing it. It is again to be 
especially noted that when the roller 10 slips relative to paper which is 
being held, the tendency for glazing of the roller by picking up foreign 
paper particles is obviated because the roller flicks the paper particles 
therefrom as described above relative to FIG. 8. 
An alternate embodiment of the present invention is shown in FIG. 7 wherein 
roller 10' includes a foamed cellular core 11' mounted on a cylindrical 
annular metal hub 34 which receives a shaft (not shown). Otherwise roller 
10' is the same as previous embodiments. The skin 14' of roller 7 is 
relatively thick. In fact, it may be so thick that the cellular structure 
of core 11' may not be retained on the outer surface 30'. The core 11' is 
open cell foam, and the outer skin 14' fills the cells on the periphery of 
body 11' to provide an outer skin which is interlocked with the core; 
whereas in closed cell cores the skin essentially stays on the surface. 
The skin 11' may still be relatively thick while the cellular structure is 
retained on the outer periphery, this being due to the fact that the outer 
skin is absorbed by the open cells of the foam, and the resulting skin at 
its extreme outer surface possesses the pattern of the cellular structure 
of the core. It will be appreciated that rollers of this type will have 
all the advantages of the heretofore described rollers having a soft core 
and a relatively hard skin, except that when the skin is so thick that 
there is no cellular structure on the outer surface, they will not provide 
the action due to the retention of air in the cellular structure on the 
surface of the skin. 
By way of specific example, the roller 10 of FIG. 1 is approximately 3/4 of 
an inch in diameter and is fabricated of open cell polyurethane foam 
having a density of about 2 pounds per cubic foot and it has about 60 
pores per linear inch. The polyurethane coating is about 0.015 inches 
thick and is applied as shown in FIG. 9 and consists of the 
above-mentioned TRANCO polyurethane polymer liquid sold under the 
designation MC-245. 
By way of further example, the roller of FIG. 7 is approximately 11/4 
inches in diameter and is fabricated of open cell polyurethane foam having 
a density of about 4 pounds per cubic foot and it has about 100 pores per 
linear inch. The polyurethane coating is about 3/32 inches thick and is 
applied as shown in FIG. 9 and consists of the above-mentioned TRANCO 
polyurethane polymer liquid sold under the designation MC-245. 
It will be appreciated that while the foregoing description referred to the 
skin as being polyurethane, other liquids may be applied as a skin and 
these could include polyvinyl chloride, neoprene, natural rubber, or any 
rubber-like elastic polymer which can be dissolved in a solvent which will 
evaporate, as was the case with the polyurethane liquid. The foregoing 
skins will preferably have a Durometer reading of between about 60 and 90, 
but the reading may be more or less than these values. If desired, the 
skin, after evaporation of the solvent, may have a thin hard shell which 
will only have a slight give to it. In addition, while the core has been 
described as having a specific range of both sizes and densities, it will 
be appreciated that the present invention may be practiced outside of 
these ranges. 
While the foregoing description has referred to paper-feeding rollers, it 
will be appreciated that the rollers of the present invention may have 
utility in other applications, and accordingly certain claims are not 
limited to paper-feeding rollers. 
While preferred embodiments of the present invention have been disclosed, 
it will be appreciated that the present invention is not limited thereto 
but may be otherwise embodied within the scope of the following claims.