Note: Descriptions are shown in the official language in which they were submitted.
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The present lnvention relates to the production
of tamper-proof caps for containers and more particularly
to so-called over-caps for wine bottles which eover the end
of the neck portion of the bottle and prevent tampering with
the cork while also keeping the cork area clean.
A eap of this kind usually has an end portion or
top connected to a flange or skirt by a tear strip which
surrounds the cap, and which allows the end portion to be
removed when the tear strip is torn away. The end portion
is preferably perforated to ensure that the cork can breathe.
While in the past such caps were usually made of
metal, nowadays such caps may be formed of synthetic plastics
material, by injection molding. Canadian Patent No. ~15,366,
whieh issued ~ 17, 1969 to Marcel, shows an injection
mold for molding a plastic eap with a tear strip. However,
even if the tear strip is formed while the cap is being molded,
it is still likely to be necessary to perform additional
operations on the cap, such as printing the cap with a design.
Furthermore, it is considered unsatisfactory to perforate the
end portlon of the cap simultaneously with the injection molding
step because pins forming such perforations may interfere with
plastic flow, and because possible flash formation around the
perforations may make it impossible for the cork to breathe.
In accordance with one aspect of the invention, in
a process for making an injection molded plastic cap of the
type described, the operation of forming the tear strip is
performed in a machine which is separate from the injection
molding machine and which mav also be used for piercing the
end portion of the Cap and/or for printing of the cap.
~ore specifically in accordance with the invention,
a process for making a plastic eap of the type described
comprises the steps of injeetion molding a cap having an
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imperforate end portion and a skirt (but wi-thout a tear strip),
conveying the injection molded caps to a machine having a
rotary head carrying a series of rotatable spindles which
are sized to recei~e the caps, and loading each cap onto
a spindle of the machine while that spindle is at a loading
station. Each cap is then indexed from the loading station
to a piercing station where the end portion is pierced to
provide the required perforations. The cap is then further
indexed from the piercing station, past a printing station
if required, and towards an unloading station, and while the
cap passes in orbital manner towards the unloading station
it is cut with a heated, double-edged knife so arranged as
to form parallel lines of weakness deEining a tear strip~
In accordance with another aspect of the invention,
a machine for use in the production of plastic caps of the
type described has a rotary indexing head carrying a series
of rotatable spindles sized to receive the caps, the machine
having a loading station with means for loading caps onto a
spindle at the loading station, and an unloading station with
means for removing the caps from spindles at the unloading
station, and one or more intermediate stations suitable for
example for piercing or printing between said loading and
unloading stations. A double-edged knife is situated so as
to contact the cylindrical surfaces of caps passing between
the loading and unloading stations, the knife having two
cutting edges which are spaced apart along the axis of the
cap to form lines of weakness defining the tear strip, the
cutting edges having a part circular sickle shape and being
of suitable length to maintain contact with the cylindrical
surface of the cap while causing the cap to rotate through
substantially one revolution. Adjacent ends of said cutting
edges have a connecting portion which is arranged to cut
through the thickness of the cap material and thus to form
an outer cut end of the tear strip.
The knife is preferably heated by a thermostatically
controlled electrical resistance heater.
The invention will be described in more detail
with reference to the accompanying drawings, in which:-
Figure 1 is a view, partially sectioned, of the
cap which is produced in accordance with this invention;
Figure 2 is a diagrammatic elevation of the
rotary head of the machine with associated conveyors, printing
mechanism, and knife;
Figure 3 is a diagrammatic plan view of the main
components of the machine, with the printing mechanism
removed for clarity;
Figure 4~ which with Figures 5 to 7 appears on the
same drawing sheet as Fig. 1, is a partly sectioned view oE
the piercer device;
Figure 5 is a front elevational view of the knife
which forms the tear strip;
Figure 6 is a sectional view on lines 5-5 of Figure
4; and
Figure 7 is a view on lines 7-7 of the lower end of
the knife.
As seen in Figure 1, the cap comprises an end
portion 1 connected to a skirt by a tear strip 3. The
majority of the length of the tear strip is defined by two
parallel rows of short narrow slits which penetrate through
the majority but not necessarlly the whole thickness oE the
sidewall, and form lines which can easily be torn. The end
portion 3a of the tear strip which extends perhaps 1 centimeter
is formed by cuts which do penetrate completely through the
wall of the cap, and due to the resiliency of the material
there is a tendency for the outer end of portion 3a to flex
Itwardly sli~htl~ from the surface of the cap so that this
can easily be grasped. The cap additionally has a band 5
of enlarged diameter which is adjacent the ~ear strip, and
the main section of the skirt adjacent the ban~ 5 has wedge
shaped projections 6 designed so that the cap can be pushed
onto the neck of a wine bottle and the projections ~ will
snap past a bead at the end of the neck and hold the cap
onto the neck. The cap is preferably printed with a design
such as that indicated at 8, and which may identify the wineO
The cap also has perforations la formed in the end portion
1, which allows the cork to breathe.
The cap is formed with all the items shown excep-t
the perforations la, the tear strip 3, and the printed
design 8, in an injection molding machine which is not part
of the present invention. The caps are taken from the
injection molding machine and loaded onto a feed conveyor
10 shown in Figures 2 and 3. This conveyor has two sprocket
chains which hold between them a series ofrollers 11 in
pairs, each spaced pa.ir of rollers rotatably supporting one
of the caps as indicated in Figures 2 and 3. While moving
along the conveyor, the caps are heated by a gas flame
heating device 12 which heats the caps by a gas flame while
simultaneously rotating the caps to ensure evennessof heating.
Rotation is achieved by pushing the caps by means of a
rotatable pusher against a rotating disk aligned with the
conveyor, while the conveyor is stationary for a short time
interval. The gas heater is similar to heating devices
existing on other machines and is not a part of the present
invention.
The conveyor 10 feeds the caps step by step
towards the loading station A of a multi-spindle turret
machine, which is basically a printing machine of the type
S ~
.~ sold under the trade mark orqso and identiied as ~&~0
Automatic Screen Printing Machine Model.R5-30H.
The mach.ine has a rotary head lS
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carrying six spindles 16 which project parallel to the
rotational axis of the head, and the head has an indexing
mechanism of well known type which rotates it in steps of
60 to move the spindles between successive stations
A, s, C, D, E, and F. Of these stations:-
A is the loading station;
B is the piercing station for forming perforations la;
C is the printing or paint applying station forapplying the patt~rn 8;
E is the unloading station. While no operation is
performed at station D, between stations D and E the tear
strip 3 is cut by a knife to be described. At station F the
spindle is empty~
The spindles 16 each include a stem 16a projecting
out of the head 15, and a freely rotatable sleeve 16b which is of
slightly larger diameter than the stem and which is a snug
fit within the ski.rt 2 of the cap. At the outer end of the
spindle there is a gap between the rotatable sleeve and the
stem to accommodate piercing pins which will be described
with reference to Figure 4.
The loading station A, as indicated, includes an
end of the conveyor 10 which brings a cap into alignmenk with
a spindle 16. The station also includes a pusher bar which is
not shown but which is a metal cylinder carried by the
piston rod of air cyl.inder 1~ shown in Figure 3. Air cylinder
18 is operated automatically to push the cap onto the spindle
: at station A.
- Station B includes the piercer shown in detail in
Figure 4, and which is aligned with the cap when in station
B. The piercer includes a bushing 20 slidable on a co--axial
rod 22 ~7hich forms the piston rod of an air cylinder 24,
cylinder 24 being mounted above cylinder 18 by an upper bracket
26. Fixed to the piston rod 22 is a collar 28, and a
compression spring 30 acts hetween the collar 28 and the
bushing 20. The bushing 20 has socket 32 which is dimellsioned
to contact the outer corners of the cap, and this leads to
a recess 33 in which is movable a plate 34 fixed to the
outer end of rod 22. At its periphery, the plate 34 carries
four piercing pins 36 which are arranged so that they can
move in between the space between the stem 16a and sleeve 16b
of a spindle, piercing the end portion of a cap to provide
the perforations la., The spring loaded bushing holds the
cap firmly on the spindle while the piercing is performed
and e-specially while the piercing pins are withdrawn from
the cap.
In the next station C the cap is printed with the
pattern 8 by printing means of known form, being for
example similar to printing means for cans. The printing
'~ means includes a paint tray 40 carried by a carriage 42 which
is reciprocable on shafts 44 so as to move horizontally in
contact with the cap as this rotates on the spindle. Also
indicated in Figure 2 are a paint applicator 46 which serves
; to push paint through the screen in the bottom of paint tray
40 as the tray moves across the cap, and a screen cleaner
48 which acts to clean the screen while the paint tray
moves in the opposite direction.
,' While in station C, and also in station D, the cap
is held on the spindle by means of a curved retaining bar 50
held by a bracket 52.
Between the stations D and E the tear strip 3 is
cut by knife 60 which is part of knife fixture 62 which is
the central feature of this invention.
The knife fixture includes a support member 64 fixed
to the face plate of the machine and having a machined under-
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side surface. Held against this undersurface is an adjustable
support 66 which has a machined surface 67 parallel to the
face plate of the machine. The fore and aft position of
the adjustable support 66 can be adjusted by knob 68 which
rotates a threaded rod to move lug 69, fixed to support 66,
relative to the fixed support 64. Against surface 67 is
held a knife assembly 70, which is similarly adjustable
along this surface by knob 72. The position of the knife
radially and axially relative to the spindle moving in
between stations D and E can be adjusted by knobs 68 and 72.
The knife assembly 70 is shown in Figures 5 and 6.
This includes a solid metal back plate 74 having a recess
for the knife 60, and an electrical heater bar 76 which is
firmly clamped onto the front surEace of the knife by
screws 78. Bar 76 includes a thermostatically controlled
electrical resistant heater which maintains the knife between
160 and 180F.
The knife 60 is a solid piece of tool steel having
~1 sickle shaped blade cut to a circular arc corresponding
to the radius of the outermost surface of the main skirt
- portions of caps held by the spindles, relative to the center
of rotary head 15. As seen in Figure 6 and 7 the knife is
formed with two cutting edges 60a, 60b by having a groove
cut in its curved edge, the groove extending along the
majority of the length of the curved edge but termina-ting in
a curved end just short of the lower end of the knife. The
cutting edges are formed by grinding the outer lands of the
groove so that they form sharp edges with the straight inner
sides oE the grooves. Additionally/ the main length of the
cutting edges are serrated so that these are interrupted at
intervals of about 1/10 of an inch. An unserrated, ~J-shaped
connecting portion 60' connects the lower ends of the serrated
cutting edges; portion 60' is designed to cut completely
through the cap wall.
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The knife is shaped and arranged so that the upper
ends of the two cutting edges contact the cylindrical surface
of the cap adjacent the end portion 1, just as this leaves
the station D. The cap is then rolled in contact with the
cutting edges which maintain the position of the cap on the
spindle so that the retainer bar 50 is not needed to hold
the cap once the knife has made contact. The main part of
the knife makes a series of elongated slits in the plastic,
through a large portion at least of the thickness of the
plastic, these slits being connected by uncut portions to
provide parallel lines of weakness. The length of the knife
blade is slightly greater than the circumference of the cap
so that there is some overlap between the cuts formed by
the upper end of the blade, and the end portion 3a which
is completely severed from the cap by the U-shaped portion
60a of the blade.
" Upon reaching station E the cap is removed from
the spindle by an unloader indicated at 80 in Figure 3,
and which includes a cylinder 82 mounted on the piston rod
83 of an air cylinder 84 and which has at its outer end a
- suetion cup 86 connected via a central bore in the piston
rod to a source of vaeuum which is connected to an end 83a
of the piston rod projecti~ng from the rear end of cylinder
84. This unloader arrangement, which is known per se, applies
vaeuum to the suction cup 86 when this is pressed against
the end of the cap, and the cylinder 84 is operated to pull
~- the cap from the spindle, at which point suction is released
and the cap drops into a cup 90 of an unload conveyor 91.
The unload conveyor 91 which again is known per se, comprises
two sprocket chains 92 connected by bars 94 carrying the cups
90, the sprocketchains being moved in timed relation to the
machine movements so that each cup recei~es one finishecL cap.
All of the operations of the machine are sequenced
automatically. Thus, the feed conveyor 10 and the off-load
conveyor 91 move in timed relation to the indexed movement
of the rotary head 15. Also, the movementsof the loader,
the piercer, the printing device, and the unloader ~0 are
all timed in relation to movements of the rotary head, so
that these operations take place while the rotary head is
stationary.
It will be seen that the invention provides a
simple way of cutting a tear strip in a plastic cap when
the cap is required to undergo operations on a multi-spindle
type machine, and the nature of the other operations being
performed can of course be varied.
It will be understood that the nature of the lines
of weakness produced by the knife may he varied; for
example these may be formed by a series of indentations or
cuts (slits), or may be an uninterrupted score line. Only
at the end portion 3a are complete through-cuts desirable.
