U.S. patent number 3,702,103 [Application Number 05/146,229] was granted by the patent office on 1972-11-07 for self-adjusting cut-off knife.
Invention is credited to Richard C. Adams, Robert W. George, Raymond E. Price, Clifford F. Tirrell.
United States Patent |
3,702,103 |
Price , et al. |
November 7, 1972 |
SELF-ADJUSTING CUT-OFF KNIFE
Abstract
A pair of cut-off knives for stripping the lower closure of a
vertical stack of closures is floated on a spring shim to be able
to ride between the curl portions of closures one of whose curl is
so oversized as to otherwise cause the knives to interfere with the
curl portion.
Inventors: |
Price; Raymond E. (Belmont,
MA), Tirrell; Clifford F. (South Weymouth, MA), Adams;
Richard C. (Waltham, MA), George; Robert W. (Belle Mead,
NJ) |
Family
ID: |
22516399 |
Appl.
No.: |
05/146,229 |
Filed: |
May 24, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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813039 |
Apr 3, 1969 |
3606850 |
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Current U.S.
Class: |
413/48;
221/268 |
Current CPC
Class: |
B21D
43/24 (20130101); B65G 59/105 (20130101) |
Current International
Class: |
B21D
43/20 (20060101); B21D 43/24 (20060101); B65G
59/00 (20060101); B65G 59/10 (20060101); B21d
043/16 () |
Field of
Search: |
;113/114R,114BE
;221/268,276,292,293 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Herbst; Richard J.
Parent Case Text
This application is a division of application Ser. No. 813,039
filed on Apr. 3, 1969, now U.S. Pat. No. 3,606,850.
Claims
What we claim is:
1. The method of cutting off and feeding can ends of a given
nominal curl height in a can end lining machine comprising;
stacking the can ends in a vertical stack; supporting the stack on
slide shelves of spaced apart reciprocating feed bars where the
slide shelves terminate at a point where they will pass beyond the
stack upon the upstream stroke of their reciprocation; mounting and
resiliently biasing upward upon the feed bars, cut-off knives,
where the upward biasing is limited to a point above the slide
shelf up to about 0.007 inch above the maximum curl height of the
can end; moving the feed bars in an upstream direction and the
cut-off knives carried thereon to cut off the lowermost can end by
the cut-off knife contacting the second lowermost can end and
biasing downward to enter between the said two can ends; supporting
the stack on the cut-off knives and the cut-off can end on the
slide shelf until the termination of the shelf permits the can end
to drop off it; moving the feed bars in the downstream direction
until the cut-off knives pass out from under the stack which then
drops onto the slide shelf.
Description
BACKGROUND OF THE INVENTION
This invention relates to container closure lining machinery, and
particularly to an improvement in the device which picks the
unlined closures from a vertical supply stack and advances them to
a rotary chuck where the lining operation is performed.
In a slide feed lining machine closures are vertically stacked in
anticipation of being transported individually to a lining station
which consists basically of a rotary chuck and a nozzle. At the
lining station a fluid gasketing or sealing compound is injected
onto the closure as it rotates on the chuck. The closure is then
transported away from the machine for subsequent operations such as
curing of the compound. Closures are fed from the vertical stack by
sliding the lowermost closure in the stack to the lining
station.
This invention deals with the means by which the lowermost closure
is separated from the vertical stack and slid to the lining
station. The lowermost closure in the vertical stack of closures is
stripped or cut off from the stack by cut-off knives, dropped to a
slide table, and moved downstream to the rotary chuck. The device
which performs this function is formed by two reciprocating
parallel slides spaced apart a distance somewhat less than the
diameter of the closure. The cut-off knives are mounted upon and
above the slides for a coincident reciprocation. A vertical space
is left between the slide and the knife suitable to receive the
lower closure after the knives have cut it off from the stack. The
stack rests on the slides until the knives cut off the lower
closure at which time the stack rests on the knives, the lower
closure dwelling in the space until it is dropped to the slide
table, whereupon it is transferred to a rotary chuck for the lining
operation.
The space between the slide and the knives must be of sufficient
height to accept the "curl" of a can end or the "skirt" of other
closures. In addition, the edge of the knives which cut off the
lower closure must not be so high as to interfere with the curl of
the second lowest closure nested in the lowest closure. It would be
possible to set the height of the knives just right if the height
of the curl of every closure were dependably consistent. However, a
variation in closure dimensions must be anticipated due to the
realities of their manufacture. Conventionally, the cut-off knives
are set by a gauge to 0.002 of an inch over the maximum curl height
expected. If a closure exceeds this dimension, a jam may occur. If
the knife is set higher, it will not be able to work itself between
the closures and will frequently damage the second lowermost
closure.
The tolerances which are maintained by the closure industry are
remarkably close. Some closure manufactures produce shells with a
0.002 inch tolerance, others however, keep only a 0.005 inch
tolerance. Some closures have dimensions outside the specified
tolerances. Therefore, among the billions of container closures
which are made, some appear which cause difficulties in the feed
mechanism and lead to jams.
The out-of-tolerance dimension which causes the greatest trouble is
the vertical height of the curl. If that dimension exceeds by more
than 0.002 of an inch the tolerance limit, the cut-off knives will
smash against the closure and cause a machine jam which
necessitates shut-down and clearing the machine. Freeing the jam
can be a time-consuming operation. Consequently, any device which
successfully passes on closures slightly out of tolerance (provided
that tolerance is demanded solely because of the characteristics of
the lining machine) is economically advantageous.
We have discovered that by mounting the cut-off knives on the slide
so that they are free to float vertically through a small distance,
and shaping the end of the knife so that it is tapered both
longitudinally and transversely, the knife can be set as much as
0.007 inch above the curl height tolerance limit and still work its
way between closure and closure, cause the supply stack to ride on
the knife, and push the just-fed closure ahead towards the chuck.
Closures which are as much as 0.005 of an inch over or below the
present-day tolerance limits can now be successfully fed.
SUMMARY OF THE INVENTION
The cut-off knives of a strip feed lining machine are floated in a
controlled manner and may have edges which are tapered both
longitudinally and transversely in order to permit cut off of the
lowermost closure of the stack without jamming.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be better understood from the specification and
from the drawing in which:
FIG. 1 is a perspective view of the slide-feed lining machine on
which the invention is used;
FIG. 2 is a plan view of the left- and right-hand cut-off
knives;
FIG. 3 is a cross-section on line 3--3 of FIG. 2 of one arm of the
feed slide;
FIG. 4 is a plan view of the cut-off knives;
FIG. 5 is a cross-section on line 5--5 of the cut-off knife of FIG.
4;
FIG. 6 is a plan view of the self-adjusting spring shim;
FIG. 7 is a side view of the self-adjusting spring shim;
FIG. 8 is a side view of an alternative configuration for floating
the knives;
FIG. 9 is a perspective view of another embodiment of the cut-off
knives.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In FIG. 1 is shown the slide-feed lining device of which the
cut-off knives of the present invention are a part. Closures are
supplied from a stack 1 to be delivered to a lining station 2 from
whence they are subsequently transported to a take-away apparatus
shown as a conveyor 3. The device is shown with feed bars 4 and 5
at the end of their forward or downstream stroke having delivered
an unlined closure 6 to the lining station 2 and at the same time a
lined closure 7 to the conveyor, which latter closure had been at
the lining station. On their return or upstream stroke the feed
bars 4 and 5 will separate the lowermost closure from stack 1 and
drop it to the slide table 8. Upon the forward stroke, the closure
will be slid along the slide table 8 to the lining station 2. The
stack 1 is located by a block assembly 9 fixed by a means not
shown, to the slide table 8. The right hand feed bar 4 and the
left-hand feed bar 5 is thus reciprocally driven in unison, by a
means not shown, along the path of closure movement.
The present invention deals with the means by which the lowermost
closure is separated from the stack for subsequent delivery to the
lining station, 2, an embodiment comprised of the right-hand
cut-off knife 10 and the left-hand cut-off knife 12 which are
attached to the feed bars 4 and 5 respectively. The invention also
deals with the means by which the knives 10 and 12 are mounted. The
cut-off knives 10 and 12 serve to separate or cut off the lowermost
closure from the stack 1 for subsequent delivery to the lining
station 2.
The closures shown and described in the following description and
No. 2 can ends, and the dimensions indicated are representative
particularly of those exiting with No. 2 can ends.
Referring to FIG. 2, the feed bars 4 and 5 straddle the can ends of
stack 1 and have slide shelves 14 which extend inwardly to present
a space somewhat smaller than the diameter of the can ends. The
slide shelves 14 terminate upstream in an inclined edge 16. When
the feed bars 4 and 5 are at the downstream extreme of their stroke
as shown in FIG. 2, the stack 1 rests upon the slide shelves 14.
The cut-off knives 10 and 12 are mounted on the feed bars 4 and 5
and spaced above the slide shelves 14.
FIG. 3 taken in cross section along the line 3--3 of FIG. 2 shows
the mounting of the cut-off knife 10 above the slide shelf 14. By
way of example, the knife 10 is held in position by a NYLOK socket
head cap screw 18. The knife 10 is not secured against the feed bar
4 but rather is resiliently floated or raised upwardly against the
screw head by a spring shim 20. Thus there is a vertical space
between the slide shelf 14 and the knife 10 which may be varied by
adjusting the screw 18.
A spring shim 20 which provides this easy vertical adjustment is
shown in FIGS. 6 and 7 as a strip of spring steel which may, e.g.,
be three-eighths of an inch wide and bent as shown with 1/8 inch
offsets, approximately 11/2 inches from base to base. Spring steel
0.020 inch in thickness floats the knives nicely. A wide variety of
compressible and/or resilient materials may be utilized to float
the knives. Additional materials found suitable are laminated brass
shim stock one-sixteenth inch thick consisting of 0.002 inch
laminations or an elastomeric material such as neoprene rubber.
The knives 10 and 12 are shown in greater detail in FIGS. 2 and 4.
The leading edge 22 of the knives are ground into a particular and
peculiar double tapered shape. FIG. 4 shows one such shape which
works on No. 2 can ends in which the knives 10 and 12 have a radius
of 11/2 inches struck three-eighths of an inch offset from the
center line 24 of the two knives when mounted in position. The
taper is finished in an arc ground three-eighths of an inch above
the center line 24 on a radius of 21/4 inches and one-half inch to
the left of the 11/2 inches arc. FIG. 5 is a cross-section through
line 5--5 of FIG. 4 showing the tapered portion of the knife
edge.
In describing the cyclical operation of the device, it will be
assumed to commence from the extreme downstream position shown in
FIG. 2. The feed bars 4 and 5 are driven upstream (to the right in
FIG. 2) by a means not shown.
As the feed bars 4 and 5 move upstream, the slide shelves 14 slide
beneath the stack 1 which is held steady by the block 9. Leading
edges 22 of the cut-off knives 10 and 12 work themselves between a
lowermost can end 26 and a second lowermost can end 28 as shown in
FIG. 3. The can end 28 with the stack 1 above it is thus lifted
slightly to ride on the upper face 30 of the cut-off knife 10. The
can end 26 remains on the slide shelf 14.
The feed bars 4 and 5 continue to move upstream until the inclined
edges 16 of the slide shelves 14 pass beyond the can end 26. The
can end 26 then drops to the slide table 8. At this point the feed
bars 4 and 5 begin the forward of downstream stroke (to the left in
FIG. 2) in which the can end 26 is engaged by the inclined edges 16
and is slid to the lining station 2. The lined can end which was at
the lining station is then pushed to the conveyor 3. During the
downstream stroke the can end 28 and the stack 1 above it drop to
the slide shelf 14 as the knives 10 and 12 are withdrawn.
With reference to FIG. 3, in the past the distance between the
knife 10 and the slide shelf 14 was fixed at the most 0.002 inch
over the maximum tolerance of the height of the curl 32. The knives
could not be set any higher because they could then crush the can
end 28. Jams therefore occurred if the curl portion 32 of the can
end 26 was higher than the space between the knife 10 and the slide
shelf 14. By floating the knives in the manner shown, it is
possible to handle can ends where the curl height varies as much as
0.005 inch over the tolerance limit. In this case the knives 10 and
12 are set as much as 0.007 inch above the expected maximum curl
height. As the leading edges 22 of the knives hit the can end 28,
they are pushed downward against the force of the spring shim 20 to
enter between the can ends 26 and 28. The resistance of the spring
shim 20 may be chosen and adjusted by a skilled mechanic
sufficiently to keep the knives floated upward, but still allow
them to move downward upon contacting the can end 28.
In FIG. 8 is shown a further development of the concept in which a
knife 10 is spaced above a shim 34 which may comprise any of the
materials or shapes mentioned but which is cut back behind the
tapered portion 36 of the knife 10 so that the resilience of the
knife 10 itself may in whole or in part provide the desired
floating effect.
Floating the cut-off knives in the manner described has made a
remarkable improvement in reducing jams. Only very rarely will a
can end come through with dimensions outside the operating limits
of this spring-floated cut-off knife, providing much more constant
operation of machines so equipped.
FIG. 9 shows a further embodiment in the double tapered knife edge
having the advantage of lower cost and superior performance. The
embodiment of FIG. 9 is especially characterized by having no
compound surfaces, a smaller angle of entry between the closures,
and entry at a point of greater closure strength.
Thus the knife 38 shown has a longitudinal ramp 40 which is at an
angle to the upper surface 42 of about 1.degree.-5.degree., about
2.degree. 12' being preferred. It also has a transverse camming
surface 44 which is struck downward from line 46 at an angle of
about 20.degree.-25.degree. degrees. Finally, the leading edge 48
extends rearward at an angle of from about 10.degree.-20.degree. to
the longitudinal axis of the knife 38 having a preferred angle of
about 12.degree.. By this configuration the leading edges 48 enter
between the can ends 26 and 28 at points more nearly diametrically
opposed and upon a line more nearly tangent to the periphery of the
ends at the point of entry.
* * * * *