Weighing scales – With testing
Patent
1993-01-06
1995-08-08
Fuller, Benjamin R.
Weighing scales
With testing
G01G 1952
Patent
active
054400767
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an automatic weighing apparatus for weighing a bulk product of particle-like material such as grain for example, by dividing it into discrete loads (so-called batches), determining the mass of each discrete load in sequence, summing the weighing results and delivering the discrete loads to bulk.
The apparatus is provided with a weigh hopper, means of automatic supply and discharge of the particle-like material to and from the weigh hopper respectively, means for weighing the weigh hopper consisting of a number of electro-mechanical loadcells at a number of suspension points for sensing the weight of the weigh hopper and for giving an electric signal which is proportional to the force excerted on the loadcells concerned and which is used for controlling the means of supply and discharge, and in which the means for checking the correctness of the measured weight values given by the loadcells are present to enable a final and correct determination of the total weight of the weigh hopper.
An apparatus of this type is known from NL-A-7413191. Alongside the obligation to check automatic weighing machines (equal batch weighers and gross/tare weighers) at regular intervals by means of certified test weights, it is also necessary in the world grain market to have a checking facility incorporated in the automatic weighing apparatus to enable monitoring the indicated weight during operation. ("dynamic check")
In the interest of the world grain trade the automatic weighing equipment in accordance with NL-A-7413191 is therefore fitted with a so-called "check scale".
This check scale consists of a pro-weight platform (with a ratio of e.g. 10 to 1 or 100 to 1) or a graduated weigh beam (with sliding poise) which can be coupled via a change-over device to the lever system of the weigh hopper.
By stopping during operation with a full or an empty weigh hopper, the contents of the weigh hopper can be determined by means of placing proportional weights on the pro-weight platform or by means of positioning the sliding poise on the weigh beam until equilibrium is achieved.
The result can be compared with the weight as indicated on the dial or another form of weight indicator.
A weighing apparatus with such a check scale has a number of objections; subject to wear and tear and the possibility of breakdowns. errors in the transmissions are detected. carried out at the weighing machine itself. A "remote control" is not possible. disadvantageous for both the supply and discharge routes should these checks take too much time. carried out "correctly".
The object of the invention is to overcome these objections and to provide a weighing apparatus in which the check weighing function can also be automated fully electronically.
This object is achieved by this invention inasmuch that the means of weighing the weigh hopper and of controlling the supply and discharge devices consist of among others the signal of primary electro-mechanical loadcells and that the means of check weighing consists of secondary electro-mechanical loadcells of which the electrical signal is compared with that of the primary electro-mechanical loadcells.
Through the use of this invention a fully electronically automated process of weighing and check weighing is achieved. Furthermore, by using loadcells, a fast reaction and setting time is obtained through the arrangement of the loadcells and their minimal deformation.
According to a preferred embodiment of the invention a number of combined units of primary and secondary loadcells are fitted in series mechanically at each suspension point in such a manner, that the secondary loadcell is subjected to the same load (less a constant weight of certain components) as the primary loadcell of the same unit and the signal therefrom is checked.
This method effects a great simplification of the check weighing and its electronic processing.
Furthermore according to another favoured embodiment of the invention, the combined units comprise of a U-shaped frame arranged horizontally so that the primary
REFERENCES:
patent: 3828869 (1974-08-01), Sellers
patent: 4499961 (1985-02-01), Fukuda
patent: 4515231 (1985-05-01), Ishida
patent: 4582454 (1986-04-01), Brandenburg et al.
Eerste Nederlandse Fabrlek van Weegwerktuigen Jan Molenschot BV
Fuller Benjamin R.
Gibson Randy W.
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