Filling machines

Disclosed are method and apparatus for determining and assuring correct fill weight of containers. In one embodiment electro-optical weigh cells are employed in conjunction with weigh dump receptacles. A second embodiment discloses addition of a second container weighing operation with addition of optional additional fill operations.

BACKGROUND 
This invention relates to the subject matter of U.S. Pat. No. 4,407,379 
issued Oct. 9, 1983 the disclosure of which is hereby incorporated by 
reference. 
One of the problems of making filling machines, especially for hard to 
handle substances, is that one cannot be assured when filling any one 
package that the weight is right. Therefore, it is often needed to add 
more to it (or remove material), also called "dribble fill". The question 
is, how to do this at high speed and high accuracy? 
One approach has been shown in the above mentioned, U.S. Pat. No. 4,407,379 
which allows containers (packages) to be weighed on-the-fly and their fill 
weight corrected. Disclosed herein is an improvement wherein a combination 
of weigh/dump cells, according to the invention are transported relative 
to package carrying cells, which also may be according to the invention, 
and used to assure that the packages are filled to the correct weight. 
This invention contemplates the use of the electro-optical cells of the 
referenced patent in weigh dump receptacles such as are known in the art. 
The material is then transfered to the container and additional material 
added or removed if required. 
More than one weigh dump cell can be used to fill any given container. Via 
the invention, the weigh dump receptacles and/or the containers can be in 
continuous motion for maximum speed and reliability (a major problem with 
current weigh dump systems which must generally stop). 
A major advantage also results in that the containers themselves can also 
be weighed in such a system, allowing container tare weight to be 
accounted for and determining the extent of subsequent weigh receptacle 
dump or dribble operations to be performed.

Consider FIGS. 1(a) and 1(b). The device shown includes packages 10 
traveling along a linear line 11 optimally with weigh cells 12 of the 
patent. In the referenced invention we showed the filling (for example, by 
fill dispenser 13) of such packages and bringing them to the correct 
weight by simply weighing them at at least one point (eg. point "B") after 
first fill and adding (or subtracting) material wherein the amount added 
was controlled according to the weight. 
In one embodiment of this invention, control of additional amount of 
material is provided by a second line of weigh receptacles 30 above the 
first or displaced in some other direction (overhead however is typical 
for gravity to effect the fill) is utilized. The receptacles are shown 
here on a rotary disc 32, and may be of the same or different capacities. 
If they are the same, the process of their filling assures that they will 
have slightly different amounts in each one. These weigh receptacles 
contain weigh cells of our referenced invention and are filled at fill 
station 35 at one end and again weighed as they go around with the weight 
tracked by computer 65. When the receptacle with the correct additional 
weight (or the most correct of the given filled receptacles in the disc) 
is obtained, that receptacle is exhausted into the correct container. Due 
to the advantageous operation of the invention, all of this can happen in 
motion, and there is no need to stop. 
The moving weigh dump receptacles can move at a considerably higher rate 
than the containers and therefore overtake them, or they can move in the 
opposite or other direction to intercept. 
The size preferably of the weigh dump receptacles and/or the method of 
their loading is chosen as to always have a range of weights in those 
cells which can be used to `top off` the range of fill weights associated 
with the main filling operation. For example, random fill weights or 
computer optimized random weights can be used. 
It is noted that just like in the reference patent, the tare weight of the 
packages can be removed from this weight calculation by loading the 
unfilled containers on, and at a first point, `A`, measuring them 
according to the invention. In addition, the containers can be weighed 
after the dumping of the initial charge and further corrections applied. 
This technique is very powerful and can be used for just about anything, 
including liquids. Particularly it could be used for high speed products 
such as munitions, beer cans and hard to fill substances like potato 
chips, corn flakes, etc. 
The invention can clearly be built all in an "all rotary", all linear, or 
any other suitable fashion. Two rotaries, one over the other, can be used 
for example. 
It is noted that the rotary on top has to dump within the short tangential 
zone of the rotary that allowed for filling when correct container, 
receptacle is brought in to place. Rotary motion gives a smoother motion 
allowing higher speeds than the linear. Therefore, the linear moves 
slowly, the rotary fast. 
FIG. 2 shows a detail of one type of weigh receptacle according to the 
invention. The receptacle 30 is mounted to rotating disc 32 by elastic 
members 50 which deflect in proportion to the weight of material in the 
receptacle thereby changing width w between edge members 51 and 52. This 
width w is monitored by an imaging or diffraction based measurement system 
(such as with laser 45 and photodetector camera 46 in FIGS. 1a and 1b as 
the receptacle comes around in its motion past a weight measurement point. 
Alternatively, only edge 51 needs to be monitored if the weigh disc 32 is 
well known in its location relative to the measurement sensor. However, it 
is generally best to monitor both reference edge 52 and moving edge 51. 
Fill material is held in weigh receptacle 30 in one example by gate 57 
actuated by solenoid 58 controlled by computer 65 which causes it to dump 
at the correct instant (when a container is underneath). Initial width 
w.sub.o can be first determined when no fill inside and the initial 
receptacle tare weight determined (and stored in memory for that 
receptacle). Fill weight is thus proportional to w.sub.o -w.sub.f where 
w.sub.f is the decreased width when filled. 
Another aspect of the invention is that all the filled receptacles do not 
have to dump--that is they can keep going around until they are used. 
Interestingly, the same applies to the containers. Since the device is 
recirculating, particularly the rotary versions, the container (or 
receptacle) can keep going around until it receives its correct fill. One, 
however, has to have a mechanism for not loading another empty container 
onto the same weigh cell where the partly full one is. 
Because of the fact that the packages can keep going on and on and still be 
on the same weigh cells, at only the price of extra weigh cells, one could 
actually have a plurality of these types of weigh dump conveyors and 
essentially give the system more than one chance to top off a container so 
to speak. Other types of dribble fill can also be used. 
This idea of containers or receptacles recirculating until they reach a 
correct fill weight is a new one and potentially of considerable interest. 
A computer such as 65 tracks the progression of container (or weigh 
receptacle) as it recirculates through at least one filling station and/or 
at least one trim (dribble) station. The weight after each fill is 
measured at at least one weigh station which also may be used to sense, if 
desired, the tare weight of the container. 
The recirculating system can be built in rotary, linear or any other 
convenient arrangement. As the container fills, its weight is measured and 
additional amounts "injected" (dribbled) each pass until full to the 
desired weight. 
The rate (in filled containers per hour, say), is dependent on the rate of 
correct fill of the previously loaded containers. If too many passes are 
required on the average to fill a container, the control computer may 
increase the fill amount(s), primary or dribble, to cause a quicker 
reaching of correct weight (but perhaps with less accuracy of that 
weight). 
The rotary fill mechanism where each item is released only when ready, 
allows highly accurate rates to be generated. While the invention 
comtemplates a revolving or otherwise recirculating fill means which would 
deposit for example the same amount of dribble fill each time, it is also 
possible to have a variable amount put in under control of a command 
computer. This variable amount could be put in from a variable fill and 
dump or using flow control means known in the art. No container leaves 
until it is filled within some certain tolerance span which is adjusted on 
an ongoing basis to allow the desired throughput rate to be maintained 
while still satisfying economic goals or governmental restrictions. 
The actual means for unloading the rotary weigh cells is via a pusher arm 
or other suitable device for pushing the containers off which can be 
actuated on demand. 
One could also have a weigh dump conveyor going along with the other 
conveyor that actually removes material from the package. For example, a 
vacuum hose sucking corn flakes out of a box would be the reverse of a 
filling nozzle going down in the box from overhead. In other words, you 
only suck out just the little bit that's required where you do the main 
fill by some dump cycle. A shuttle arrangement for dumping or sucking is 
shown in FIGS. 1a and 1b. 
Corn flakes packages such as 10 for example, travel on a continuous layer 
conveyor 11 with weigh cells according to our previous patent. Overhead 
shuttle unit 200 moves in conjunction with the line for a limited period 
of time and sucks out with hose 201 some of the material until the weight 
becomes correct as measured by the system disclosed in our previous 
patent. 
After the material is removed, the shuttle rapidly traverses back to be 
ready for the next package. 
Relative to FIGS. 1a and 1b, it is noted that alternately the total fill 
can be provided by the weigh dump receptacles eliminating the need for 
fill dispensor 13 and weigh check `B`. In this case, one receptacle can 
dump the most correct load nearest final fill weight into a container 10, 
or a plurality of successive dumps by receptacles 30 can be made until the 
correct weight is attained. A best fit approximation can be used to 
provide the best approximation of final fill weight from the choices 
present in the pre weighed filled receptacles 30.