Sheet metal container making – Method – Assembling receptacle with closure
Reexamination Certificate
2000-04-25
2003-09-09
Sipos, John (Department: 3721)
Sheet metal container making
Method
Assembling receptacle with closure
C413S002000, C413S001000, C053S272000, C053S276000
Reexamination Certificate
active
06616392
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a method and apparatus for varying the canister throughput rate in a rotary sealing turret while maintaining consistent sealing times per unit and, in particular, to the use of an indexing clutch system that controls the feeding of canisters into specific turret positions while the turret maintains a constant rotational speed. The invention allows for wide variations in production speeds without the need for excessive speed ramping or sealing application adjustments.
2. Description of Related Art
There exists in the canning and food packaging industries a number of different methods for sealing “cans” or “canisters,” which terms are used interchangeably throughout this applications. The methodologies available, however, are greatly narrowed when the can or canister that must be sealed has, for example, an elliptical shape and a paper or cardboard bottom, such as the canisters shown in
FIGS. 1
a
and
1
b.
Such canister typically may comprise an elliptical tube
102
(or other shape such as round, triangular, or square) made of paper or cardboard and layered with other material to provide the necessary barrier properties and is used as a vessel for holding a product, such as potato chips. The elliptical tube
102
typically arrives at the food packaging line with a hermetic removable seal
104
placed on a first end with a plastic over cap
106
seated over the removable seal
104
, although it also might arrive with the first end open and the second end sealed. The canisters illustrated in
FIGS. 1
a
and
1
b
are shown inverted, since the removable seal
104
and overcap
106
will be oriented at the top of the canister when displayed for sale.
A food product, such as potato chips, is deposited in the open second end of the canister, which is then sealed by a paper or cardboard end cap
108
. A paper end cap
108
is preferred to a metal end cap due to manufacturing cost savings of three to five-fold involved in using the paper end cap.
The sealing means used to apply the paper end cap
108
to an elliptical canister in the prior art is a sealing machine applying a heat and pressure seal using a rotary sealing turret having a plurality of sealing heads, such as those manufactured by Blema Kircheis of Germany. During the heat-sealing process, such machine seals the end cap
108
to the inner and outer sides of the tube
102
.
An overhead schematic of a typical prior art sealing machine in this regard is shown in FIG.
2
. Open and filled canisters
220
, oriented as illustrated in
FIG. 1
a
with the open end up and without the paper end cap installed, are placed on an input conveyor
222
. The containers
220
proceed down the conveyor
222
and are received in an indexing clutch
224
. The indexing clutch
224
regulates individual canisters
220
into channels on a timing or worm screw
226
such that canisters
220
are deposited at evenly spaced intervals on the timing screw
226
. The timing screw
226
then provides the needed separation between the canisters
220
for placement in an infeed star wheel
228
. The infeed star wheel then places a canister in each of one positions
230
of a rotary turret
232
. The end caps are fed from a second station and deposited in a sealing head. Sealing heads (not shown) located above each position apply the end caps to the open end of each canister by asserting heat and pressure to the end caps as they are sealed on the canisters. The rotary turret
232
illustrated in
FIG. 2
comprises an 8-head configuration, with each head position marked 1 through 8. However, rotary sealing machines can be constructed with any number of heads typically varying from 2 heads to 12 heads.
The end cap is applied over the open end as the canisters
220
enters the rotary turret
232
. The sealing head then applies heat and pressure to the end cap to activate the sealing properties of the end cap as each canister rotates through 270° around the sealing turret
232
. The dwell time for the application of the heat and pressure is dependent on the rotational speed
250
of the rotary turret
232
. After the end cap is attached, the now sealed canisters
221
are fed onto an outfeed conveyor
234
by an outfeed star wheel
236
.
Typically, the pressure applied by the sealing heads is fixed in accordance with the manufacturer's specifications for the sealing machine. The rotational speed
250
of the turret
232
(or resultant dwell time) and the temperature applied to the canisters
220
while in the turret
232
, however, are both adjustable to compensate for the particular composition of the end caps. For example, end caps of varying thickness but made of similar material could require varying dwell times or temperature settings, or a combination of both, in order to optimally activate the end cap's sealing properties. Further, the dwell time and temperature applied can vary between caps using different materials with varying activation temperatures. By way of example, a composite paper cap of 13 pts thickness having a 25 g/ml sealing layer coated over a foil layer works best with a dwell time of 1.8 seconds at 160° C. However, a thicker end cap would require a longer dwell time, and an end cap using a material having a different sealing activation temperature would require a different sealing temperature.
It is desirable that the composition of the paper end cap remain constant during different canister applications for various reasons, such as quality control, consistent packaging presentations, inventory costs, and manufacturing costs. Unfortunately, once a particular type of end cap is selected, the dwell times and temperature settings are relatively inflexible. Consequently, the throughput of the sealing machine can only be varied slightly (10% or less) through what is referred to as “speed ramping.” Speed ramping involves concurrently changing the speed of all system components in order to change the throughput rate. The inability to vary the throughput significantly using prior art methods gives rise to a significant production problem.
By way of example, it may be desirable to radically change the throughput of a single sealing machine in order to compensate for different canister sizes or production line volumes. On an 8-head turret, a typical paper based end cap with a sealant laminated inner surface, subjected to a 1.8 second dwell time at 220° C., results in a throughput of approximately 200 canisters per minute. However, slowing the turret down to produce a throughput of 50 cans per minute results in a dwell time of approximately 7.2 seconds. A paper based end cap exposed to 220° C. for 7.2 seconds would result in burning. However, lowering the temperature of the sealing heads sufficient to avoid burning would not activate the sealing material regardless of the longer sealing time. In order to stay within the temperature and dwell time constraints, speed ramping typically can only adjust the throughput of a sealing machine by about 10% without requiring a change in the composition of the end seals.
The inability to change the throughput of a sealing machine beyond minor speed ramping adjustments is problematic when throughput requirements change drastically. Such throughput requirements may be a result of changing the canister size from, for example, an 8-oz. canister to a 2-oz. canister. Typical food processing efficiencies require that the sealing machine run at a speed sufficient to handle a constant output of product from the product lines, regardless of the ultimate canister size. Thus, to handle the same volume of product while sealing 2-oz. cans would require a four-fold increase in the sealing head speed as compared to sealing 8 oz. cans. Such radical changes in the throughput of the sealing machine are simply not feasible in the prior art. The only alternative available in the prior art is to purchase a number of sealing machines, at a cost of typically $650,000.00 per machine, and run the machines in combination or alone in order to ad
Cahoon Colin P.
Carstens Yee & Cahoon, L.L.P.
Huynh Louis
Recot Inc.
Sipos John
LandOfFree
Input control for rotary sealing turret does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Input control for rotary sealing turret, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Input control for rotary sealing turret will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3048557