Weighing scales – Computer – Electrical
Reexamination Certificate
2000-06-23
2001-07-31
Gibson, Randy W. (Department: 2859)
Weighing scales
Computer
Electrical
Reexamination Certificate
active
06268571
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to weighing methods and systems for a collected batch of a plurality of solid, flowing ingredients, and more particularly, to a computerized high accuracy industrial weighing system incorporating a plurality of weighing machines for weighing and transferring the ingredients batches in an efficient manner into a mixer.
A common method of weighing collected batch of a plurality of ingredients, known in the art of industrial weighing technology, includes the steps of alternate, in succession, weighing each of a plurality of ingredients within a single weighing hopper. The collected batch is weighed according to a target weight value set for each type of ingredients then discharged for transferring into a mixer.
A batch weighing device, well known in the prior art, generally includes a plurality of separate storage hoppers or bins. Each storage hopper is provided with a screw auger or the like for conveying the desired amount of each individual ingredient into a common weighing hopper to create a batch of selected amounts of selected ingredients. A weighing hopper is generally supported by three or four load cells so that its weight may be accurately monitored, and the cumulative weight of a mixture determines the amount of each ingredient to be added to the hopper. The great advantage of this method is the simplicity of the related weighing system. There is only one feeder for each ingredient and one weighing hopper for a plurality of ingredients. The adverse effect on the overall economy of this method is that a smaller quantity of ingredient being measured, the lesser accurate measurement is made. Thus, if the collected batch includes ingredients of the relatively large and the relatively small weight, a measuring error of small weight ingredients would be out of the normal tolerance limits.
Another well known in the art weighing system is so called the loss-in-weight system. The related method includes the steps of weighing each ingredient within a single weighing hopper, and a plurality of ingredients within a plurality of associated weighing hoppers. The collected batch is weighed according to target weight value set for each type of ingredients then discharged by discharging feeders associated with weighing hoppers for transferring into the mixer. First advantage of this system is its simplicity. There is one weighing hopper with one discharging feeder for each ingredient. Second advantage is alleviating the problems of ingredient sticking and late ingredient in flight. For example, the weighing system described and claimed in U.S. Pat. No. 5,035,294 entitled “In place bin weighing device for batch weigher” to Volk, Jr. (1991) intended advantageously to add some new feature to the known weighing system as using a single load cell with the supporting flexures to accurately weigh a bin (weighing hopper). Some disadvantages of this system are the substantial reduction in the net weighing range, causing by a relatively heavy discharging feeder associated with a weighing hopper, and the decrease in weighing accuracy. Particularly, some additional disadvantages of the weighing system described and claimed in U.S. Pat. No. 5,035,294 are the deficiency of overload preventive ability, difficulties to detach the load cell when necessary to change the last. Additionally, there is some lack of a framework to serve the upper part of bins or detach the bin.
In the weighing system described and claimed in U.S. Pat. No. 4,094,368 entitled “Load cell overload protection system for weighing scales” to Sann et al. (1978) most disadvantages of the weighing system described and claimed in U.S. Pat. No. 5,035,294 are eliminated, but still there is necessary to simplify a force-transmitting system, to integrate a load receiving structure within a self-sufficient weighing scale unit forming an entire functionally and metrologically accomplished and transportable weighing scale module.
Over the past three decades, many advances have been made in improving the efficiency of described above common methods and systems due to the computer control techniques. However, high weighing accuracy is not achieved at weighing a collected batch of a plurality of different ingredients including ingredients of the relatively large and relatively small weight, hygroscopic, adhesive, and fluid ingredients.
Actually, the most advanced weighing methods and systems are known in the technology of computerized combinatorial weighing. The advantage of combinatorial weighing is the increase in a speed. However, the greatest advantage of combinatorial weighing is the substantial increase in weighing accuracy because of peculiar to combinatorial weighing an averaging mechanism, which exactly responds to probabilistic nature of weighing errors. The methods and systems of combinatorial weighing can be applied to industrial weighing of the collected batch of different ingredients. Particularly, for the ingredients of the wide range of the weights and properties these methods alleviate the problems of ingredient sticking and the late ingredient in flight and eliminate an influence of a low resolution at weight measuring.
However, major obstacles for using combinatorial weighing are an enormous number of feeder and weighing hopper units per each ingredient and the relatively small capacity of weighing hoppers. In fact, the combinatorial system described and claimed in U.S. Pat. No. 5,736,683 entitled “Multiple hopper weighing and transfer system” to Howard (1998) intended three hoppers in each lane of a weighing machine. While there is the advanced opportunity to obtain more batches for combinatorial process or to increase the batch weight, still a number of components including drives, is truly large.
Partially, the last problem was abated in the combinatorial system described and claimed in U.S. Pat. No. 4,678,046 entitled “Combination weighing apparatus for two combined products” to Mosher (1987). This system is adapted to weigh quantities of two or more different types of products and mix them together. The system includes a plurality of weighing scales divided into two groups, one group weighing quantities of a first type of product and the other group weighing quantities of a second type of product. A computer is provided to search the first group of scales and select a combination, which contains a combined quantity of the first type of product near in the weight to the predetermined fractional target weight, and search the second group of scales and select a combination, which contains a quantity of the second type of product near in the weight to the difference between the target weight for both products and the weight of product within the combination of scales selected from the first group. The selected scales of both groups empty into a common discharge chute after weighing and searching are completed. The scales of both groups are dumped at times such that both products arrive in the common discharge chute at the same time, mingle, and mix with each other. There are only one dome-shaped vibratory feeder with a partition and one common chute for two groups of different type products. However, two loading conveyors, at least five vibrating chutes, and five weighing hoppers serve each product.
Another combinatorial weighing method and system described and claimed in U.S. Pat. No. 4,549,617 entitled “Combinatorial weighing and combinatorial counting method and apparatus” to Matsumoto et al. (1985). These combinatorial weighing method and apparatus are offered for obtaining a batch of articles of a plurality of categories, each category of articles in the batch having the predetermined weight or made up of a predetermined number of articles. The method includes the steps of setting a target value for each category of articles, and supplying a plurality of weighing machines, groups of which are provided for each category of articles, with the articles of the category corresponding thereto. For each category of articles and from all combinations of the weighing mach
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