Method and apparatus for lubricating tab stock

A lubricator (28) is provided to lubricate tab stock (82) prior to forming the tab stock (82) into pull tabs. The lubricator (28) comprises felt pads (36-38) for removing contaminants from the tab stock (82) prior to lubrication thereof. A hydrostatic chamber (40) receives and disperses lube (42) from a source (44). As the tab stock (82) passes through the chamber (40) the lube (42) coats the tab stock (82). Subsequently, the tab stock (82) passes through wipers (50-52) and metering rollers (58-60) to remove all but a predetermined quantity of the lube (42). A collector (70) is provided to collect any excess lube (42) and return same to the source (44) through a return line (72) thus allowing recycling of the lube (42).

FIELD OF THE INVENTION 
This invention relates in general to can making, and in particular to a 
method and apparatus for lubricating tab stock prior to formation thereof 
into a pull tab. 
BACKGROUND OF THE INVENTION 
In the can making art, the can body and the sealable tops therefor are 
typically made in separate operations. Similarly, in making the sealable 
tops, there are separate operations for making the top and for making the 
pull tab. Once the separate operations are completed, the pull tabs are 
affixed to the tops for subsequent sealing to the can body. 
As is well known, it is desirable to coat a metal with a lube prior to die 
punching or stamping thereof. It is desirable to lubricate the metal 
because this allows the tools to work more efficiently as well as to 
preserve the cutting edges thereof for a longer period of time. 
In the formation of pull tabs from tab stock, a length of a thin flat 
material such as aluminum is fed through a lubricating device prior to the 
formation of the pull tab. In the only type of lubricating device known to 
the applicants, a lube is dripped onto a pair of felt pads between which 
the tab stock passes. Preferably, the lube should be evenly applied to the 
tab stock prior to its formation into pull tabs. In practice, however, 
uniform application has been difficult to achieve. 
Specifically, difficulties have arisen due to accumulation in the felt pads 
of metal scraps and other contaminants. While removal of such materials 
prior to pull tab formation is desirable, the accumulation thereof in the 
felt pads will eventually clog the felt pads and disrupt the lube drip 
rate. As will be appreciated, avoidance of undesirable accumulation 
entails the undesirable requirement of shutting down the equipment to 
remove and clean, or to replace the clogged felt pads. 
Uneven lube application can also result from drip rate variations caused by 
machine vibrations and lube evaporation. In the latter regard, low 
viscosity lubes which comprise approximately 80% evaporative carrier and 
20% actual lubricant have been typically employed to accommodate the 
wicking requirements of the felt pads. That is, while lubes comprising a 
greater percentage of lubricant would be preferable from a reduction of 
evaporation standpoint, wicking within the felt pads requires a more 
watery consistency as opposed to oily consistency. 
SUMMARY OF THE INVENTION 
The invention disclosed herein comprises a method and apparatus for 
lubricating a material to be shaped which substantially eliminates or 
reduces problems associated with the above-described prior lubricator. The 
present invention allows the application of a lube to a material to be 
shaped in a more efficient and cost effective manner. 
In accordance with one aspect of the present invention, a device for 
lubricating a material to be shaped is provided. The device comprises a 
hollow container within which a set of wiping pads removes contaminants 
from tab stock prior to lubrication. Subsequent to the wiping pads, the 
tab stock enters a hydrostatic chamber which is filled with the lube. The 
tab stock is completely coated with the lube within the chamber. 
Subsequent to the application of lube in the hydrostatic chamber, the tab 
stock passes between a pair of wiper blades which remove excess lube 
therefrom. A pair of metering rollers are then provided for precise 
metering of the lube evenly on the tab stock which is then passed to the 
appropriate apparatus for forming the pull tabs. 
There is preferably a collector and run off line for catching excess lube 
from the chamber and the wiping and metering devices. The excess lube is 
then returned to a source such as a drum or tank which allows reuse 
thereof. Prior to pumping the lube back through the system, the lube is 
filtered to remove any contaminants therein, and thus a more efficient use 
of the lube is allowed than in prior lubricating devices. 
It is a technical advantage of the present invention that a more uniform 
application of lube is provided. It is a further technical advantage that 
the present invention allows recycling of the lube. It is a still further 
technical advantage of the present invention that it allows the use of 
higher viscosity lubes.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIG. 1, a partially cutaway perspective view of a lubricator 
in accordance with the prior art is generally identified by the reference 
numeral 10. The lubricator 10 comprises a container 12 having an infeed 14 
and an exit 16. 
Tab stock (not shown) such as a thin flat length of aluminum is fed through 
the infeed 14 into the container 12. Upon entering the container 12, the 
tab stock is passed between a first pad 18 and a second pad 20, each of 
which comprise felt. A lube 22 is fed to the container 12 from a drip pipe 
24. The lube 22 comprises, for example, a low viscosity and highly 
volatile lube which generally comprises 80% carrier and 20% lubricant. The 
lube 22 is fed through a hole 26 in the container 12 to the pads 18 and 20 
at a rate intended to be sufficient to keep the pads 18 and 20 soaked 
therewith. As the tab stock passes between the pads 18 and 20, the lube 22 
is applied thereto by a wiping action. 
There is no collection capability or return line in the lubricator 10 to 
allow for recycling of excess lube 22. As such, any lube 22 that does not 
evaporate, (including, for example, lube that accumulates in the pads 
18-20 if the same are flooded by an incorrect drip rate), is not recycled 
through the system, and therefore the lubricator 10 is not as efficient as 
it could be. 
Upon exiting the lubricator 10, the tab stock should be soaked with the 
lube 22 and is passed to the appropriate pull tab forming equipment prior 
to being merged with and attached to a can top. Due to the high volatility 
of the carrier in the lube 22, a significant percentage of the lube 22 may 
evaporate prior to the pull tab formation process. Thus, the pull tab 
making equipment may wear at an unacceptably high rate. 
Referring to FIG. 2, a partially cutaway isometric view of a lubricator 28 
constructed in accordance with an embodiment of the present invention is 
illustrated. The lubricator 28 comprises a container 30 for receiving the 
various parts of the lubricator 28. Tab stock 82 (see FIG. 3) enters 
through an opening 32 in the container 30 and exits therefrom through an 
outlet 34 to pull tab making equipment (not shown). 
Upon entering the container 30, the tab stock 82 passes between a first pad 
36 and a second pad 38 which wipe away any contaminants such as dirt or 
metal shavings that may be on the tab stock 82. The pads 36 and 38 may 
comprise felt or any other material suitable for wiping contaminants from 
the tab stock 82. 
After having contaminants removed, the tab stock 82 enters a hydrostatic 
chamber 40. A lube 42 which may be either a low viscosity lube similar to 
the lube 22 previously described above or a higher viscosity lube with a 
greater percentage of lubricant is pumped from a source 44 such as a tank 
or a drum through a line 46 and a feed pipe 48 into the hydrostatic 
chamber 40. As the lube 42 enters the hydrostatic chamber 40 it surrounds 
and completely covers the tab stock 82 which passes therethrough. 
After exiting the hydrostatic chamber 40, the tab stock 82 passes between a 
first wiper 50 and a second wiper 52. The first and second wipers 50-52 
may comprise any appropriate material such as, for example, rubber or a 
synthetic material capable of wiping excess lube 42 from the tab stock 82. 
The first wiper 50 is spring loaded by a tensioning device 54 (see FIG. 4) 
while the second wiper 52 is positioned in a fixed relationship thereto. 
As the wiper material is worn away from contact with the passing tab stock 
82, the first wiper 50 may be adjusted to apply the correct wiping action 
through the use of the tensioning device 54, as will be subsequently 
described in greater detail. After passing through the first and second 
wipers 50-52, the tab stock 82 passes between a first metering roller 58 
and a second metering roller 60. The first and second metering rollers 58 
and 60 have a covering thereon which may comprise, for example, Buna-N 
Rubber having a hardness of 50-55 durometers, which meters the lube 42 
from the tab stock 82 to allow only the desired thickness of lube 42 to 
remain thereon. The second metering roller 60 is fixed in position whereas 
the first metering roller 58 is spring loaded by a pressure device 62 (see 
FIG. 5). After passing through the metering rollers 58-60, the tab stock 
82 leaves the container 30 through the outlet 34 for further processing 
into pull tabs. 
Below the hydrostatic chamber 40, the wipers 50-52 and the metering rollers 
58-60 is a collector portion 70 for directing lube 42 which is wiped or 
metered from the tab stock 82 or spills from the hydrostatic chamber 40 to 
a drain hole 73. The lube 42 is passed from the collector portion 70 
through a line 72 back to the source 44. Prior to being pumped (by a pump, 
not shown) back into the container 30, the lube 42 passes through at least 
one filter 74 which removes any contaminants that may have been deposited 
therein. As a result of the collector portion 70 and the filter 74, the 
lube 42 may be reused many times over. Thus as a result of the present 
invention, a more economical usage of tab lube is possible. 
Referring to FIG. 3, a side cross-sectional view of the lubricator 28 is 
shown. The container 30 comprises a metallic support structure having a 
top portion 76 and a bottom portion 78. Fitted within the top portion 76 
and bottom portion 78 are the components of the lubricator 28. Affixed to 
the container 30 proximate the inlet 32 is a support plate and passage 80 
upon which tab stock 82 is guided to the inlet 32. 
After passing through the inlet 32, the tab stock 82 passes between the 
first pad 36 and the second pad 38 for the removal of contaminants 
therefrom. The first pad 36 and second pad 38 are positioned to allow the 
tab stock 82 to pass therebetween yet close enough together to wipe 
contaminants therefrom. After passing between the first pad 36 and the 
second pad 38, the tab stock 82 enters the hydrostatic chamber 40. 
The hydrostatic chamber 40 may comprise any appropriate material which is 
sufficiently rigid such as metal, plastic, or other synthetic materials. 
The feed pipe 48 enters the hydrostatic chamber 40 through an opening 84 
therein. As the lube 42 enters the hydrostatic chamber 40, it is dispersed 
throughout the chamber 40 and thus completely soaks the tab stock 82. 
Upon leaving the hydrostatic chamber 40, the tab stock 82 passes between 
the first wiper 50 and the second wiper 52. The wipers 50-52 are secured 
within a first roller 86 and a second roller 88, respectively. As 
previously described above, the second wiper 52 is fixed in position 
relative to the first wiper 50. However, the first wiper 50 is adjustably 
positioned in order to allow for adjustment over time due to wear. The 
wipers 50-52 press against the tab stock 82 to wipe excess lube 42 
therefrom before passing between the metering rollers 58-60. 
Referring to FIG. 4, the tensioning device 54 is shown is side elevation. 
The first roller 86 extends through a sidewall of the top portion 76 of 
the container 30 far enough to attach a spring 56 thereto. A portion of 
the spring 56 extends from the roller 86 into contact with an eccentric 
110. By turning the eccentric 110, the spring 56 causes the roller 86 to 
turn clockwise or counterclockwise to adjustably position the first wiper 
50 relative to the second wiper 52. The second roller 88 is bolted in a 
fixed relationship through a sidewall in the bottom portion 78 of the 
container 30 by an assembly 81. 
Referring again to FIG. 3, the first and second metering rollers 58-60 
comprise, for example, cylinders 90 covered with a rubber coating 92 such 
as, for example, Buna-N Rubber having a hardness of approximately 50 to 55 
durometers. The second metering roller 60 is fixed in position relative to 
the moveable first metering roller 58. To properly position the rollers 
58-60 to allow only the required amount of lube 42 to remain thereon, the 
first roller 58 is moveable with the pressure device 62. A s best seen in 
FIG. 5, the pressure device 62 comprises a spring bracket 64 
interconnected to a roller bracket 66 by dowels 68. The dowels 68 slidably 
pass through the top portion 76 of the container 30 through guide bushings 
75. A bolt 94 is secured to the top portion 76 of the container 30 by nuts 
96. The bolt 94 freely passes through the spring bracket 64. Nuts 98 and 
100 hold a washer 102 in position over a compression spring 104 (as best 
seen in FIG. 3) which is positioned over the spring bracket 64. The 
positioning of the first roller 58 is thus controlled by the tightening or 
loosening of the nuts 98 and 100 to lower or raise the roller bracket 66. 
The second roller 60 is fixed in position relative to the first roller 58 
with a roller bracket 67. Fasteners 69 pass through the bottom portion 78 
of the container 30 and are secured to the bracket 67. Spacers 71 are 
provided between the bracket 67 and the bottom portion 78 to properly fix 
the roller 60 in position. Although not shown, it is to be understood that 
other arrangements can be used to properly position and adjust the rollers 
58-60. 
In operation, the nuts 98 and 100 may be turned in a first direction on the 
bolt 94 to compress the spring 104 and lower the roller bracket 66 in a 
direction 106 and thus provide greater contact of the first and second 
rollers 58-60 with the tab stock 82. By turning the nuts 98 and 100 in a 
second direction opposite the first direction, the spring 104 is loosened 
and the roller bracket 66 is moved in a direction 108 to lessen the 
contact of the first and second rollers 58-60 with the tab stock 82. Thus 
as use of the lubricator 28 wears the rubber coating 92 on the rollers 
58-60, contact therebetween with the tab stock 82 may be adjusted to 
continuously meter the correct amount of lube 42. 
Referring again to FIG. 3, after having the correct amount of the lube 42 
metered by the rollers 58-60, the tab stock 82 leaves the container 30 
through the outlet 34. The correctly lubricated tab stock 82 then proceeds 
to the appropriate pull tab making equipment. 
Due to the present invention, tab stock is evenly lubricated with a tab 
lube, and such lube may have a higher viscosity than previously used 
lubes. Consequently, if higher viscosity lubes are used, the pull tab 
making equipment (for example, tools and dies) will experience prolonged 
lifetimes. 
Although the present invention has been described with respect to a 
specific referred embodiment thereof, various changes and modification may 
be suggested to one skilled in the art, and it is intended that the 
present invention encompass such changes and modifications as fall within 
the scope of the appended claims.