Weighing scales – Weigher responsive material control – Feed
Reexamination Certificate
1998-12-28
2002-04-23
Gibson, Randy W. (Department: 2859)
Weighing scales
Weigher responsive material control
Feed
C177SDIG009, C073S580000
Reexamination Certificate
active
06376784
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibrating transport apparatus capable of transporting a predetermined weight of articles placed on a trough for a given length of time by vibrating the trough.
2. Description of the Prior Art
It has been often experienced that when a food material such as, for example, snacks and/or candies is produced, articles in the form of granulates or the like of a raw material or a semi-processed products is transported by the use of a vibrating transport apparatus (hereinafter referred to as a vibrating feeder) from one production step to another at a predetermined supply rate, that is, in a predetermined weight for a given unitary time. The vibrating feeder of the type used in this application makes use of a weighing device utilizing a load cell for measuring the entire vibrating feeder, while the articles supplied from a supply conveyor onto the trough are transported, at intervals of a short unitary time, so that the weight of the articles on the trough of the vibrating feeder can be measured by subtracting the known weight of the vibrating feeder from the measured total weight. Based on the weight of the articles so measured, a transport amount control device of the vibrating feeder controls the transport speed of the supply conveyor on a PID (Proportional Integral Differential) control scheme so that the weight of the articles supplied from the supply conveyor onto the trough can attain a predetermined value for the given unitary time. At this time, in order to compensate for an error based on a delay in the PID control, a correction control to finely adjust the transport speed of the vibrating feeder is carried out to render the amount of the articles being transported (weight/time) towards the subsequent production step to attain a value equal to the target transport amount.
Where the articles such as snacks and/or candies are to be bagged, the articles are fragmented in a predetermined quantity by a combinational weighing apparatus utilizing the load cell referred to above.
A mechanism of the combinational weighing apparatus is schematically shown in a side view in FIG.
18
. The articles M are supplied through a supply chute
60
onto a center portion of a conical dispensing feeder
61
having a small height. When the dispensing feeder
61
is vibrated, the articles M are dispensed into a plurality of vibrating feeders
1
arranged around and adjacent the periphery of the dispensing feeder
61
and spaced an equal distance from each other in a direction circumferentially of the dispensing feeder
61
. The articles M on the vibrating feeders
1
are subsequently transported towards a corresponding number of pool hoppers
62
disposed immediately below the associated vibrating feeders
1
. After the articles M are temporarily pooled in the respective pool hoppers
62
in synchronism with a weighing operation, discharge gates of the pool hoppers
62
are opened to allow the articles M to be discharged onto associated weighing hoppers
64
. A weighing means
65
such as a load cell for each weighing hopper
64
measures the weight W of the articles M within the respective weighing hopper
64
to provide a weight signal. The articles M of which the weight W has been measured are, when discharge gates
66
of the weighing hoppers
64
are opened, collected in corresponding collecting chutes
67
and then onto a discharge chute
68
. The articles M so discharged are bagged by a bagging machine (not shown) to provide bagged products each having a predetermined target weight. Each of the weighing hoppers
64
has preset therein a target weight to which the articles M are supplied and, therefore, depending on the extent of the weighed value relative to the target value, the respective amplitudes or the respective vibrating time lengths of the vibrating feeders
1
are adjusted so that the weighed value can become equal to the target value.
With the conventional combinational weighing apparatus, the weight detection or the control of the amount of transport of the articles on each of the vibrating feeders
1
is carried out by reading the weight measured by the associated weighing hopper
64
, that is, the weight measured at a location downstream of the respective vibrating feeder
1
and not by reading accurately on a real-time basis the weight or the amount of transport of the articles on the respective vibrating feeder
1
. Therefore, a considerable time lag tends to be involved along with an insufficient response. For this reason, it has been found difficult to accomplish an accurate control of the amount of the articles to be supplied (that is, the transport amount).
Also, in the prior art vibrating feeder
1
of the type discussed above, since a load cell is used to measure the total weight of the vibrating feeder
1
having a relatively great weight, the apparatus as a whole tends to become bulky and expensive.
In addition, in the prior art vibrating feeder
1
, the control of the transport amount, that is, the amount of the articles to be transported by the vibrating feeder
1
is carried out by changing driving energies (electric driving power) to change the amplitude of vibration of the vibrating feeder
1
. Accordingly, if the transport amount is increased by increasing the amplitude of vibration of the vibrating feeder
1
, the amount of heat evolved by an electromagnetic coil tends to increase, accompanied by increase of energies consumed.
Yet, when the vibrating feeder is to be halted, the articles tends to be transported under the influence of an inertia even though the driving energies are interrupted, and therefore, an error in transport amount tends to become considerable.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been devised with a view to substantially eliminating the above discussed problems inherent in the prior art and is intended to provide an improved vibrating transport apparatus capable of accomplishing the detection of the weight of the articles or the transport amount control accurately on a real-time basis with minimized energy consumption and also having a high response exhibited when the apparatus is brought to a halt.
Another important object of the present invention is to provide an improved vibrating transport apparatus of the type referred to above, which has a simplified structure enough to allow the vibrating transport apparatus to be assembled compact in size, and which is capable of accomplishing a highly accurate measurement of the weight of the articles on the trough and also capable of highly accurately controlling the rate of supply of the articles towards the subsequent production step with a simplified control system.
A further important object of the present invention is to provide a method of detecting a vibrating characteristic exhibited in the vibrating transport apparatus of the type referred to above.
In order to accomplish these objects, the present invention according to a first aspect thereof provides a vibrating transport apparatus for transporting an article loaded on a trough by vibrating the trough in a predetermined vibrating direction, which apparatus comprises a weight detector including at least one strain gauge mounted on a portion of the transport apparatus where elastic strains are developed upon placement of the article on the trough and operable to detect an amount of the strains, and a weight detecting circuit for detecting a weight of the article placed on the trough on the basis of the amount of the strains detected by the strain gauge.
According to the present invention, since the amount of the strains detected by the strain gauge changes with change in weight of the article on the trough, the weight of the article on the trough can advantageously be detected on a real-time basis. Also, no extra weight detector is needed in the vibrating transport apparatus.
In one preferred embodiment of the present invention, the vibrating transport apparatus may further comprise an amplitude detector including an additi
Gibson Randy W.
Ishida Co. Ltd.
Staas & Halsey , LLP
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