Weighing scales – With testing
Reexamination Certificate
1999-08-18
2001-08-21
Gibson, Randy W. (Department: 2859)
Weighing scales
With testing
C073S001130
Reexamination Certificate
active
06278067
ABSTRACT:
BACKGROUND OF THE INVENTION
The aim of the present invention is to provide a simplified means of calibrating the headwork for a weighing machine.
Calibration of weighing machines can be a complex and arduous task, especially where the weighing machine has a high maximum load and calibration involves the placing of weights to give a dead load of up to that maximum load on the weight platform or in the material vessel. This may very often have to be done in conditions of poor accessibility and possible danger.
By eliminating the need to handle weights up to this maximum load and improving accessibility, the present invention eases and simplifies the calibration procedure.
SUMMARY OF THE INVENTION
According to the present invention there is provided a calibration rig for a weighing machine, the weighing machine comprising a load cell including a transducer and headwork connected to the load cell, the calibration rig comprising a load cell including a low capacity transducer having excitation voltage and signal connections arranged for connection to the headwork and a potentiometer, the fixed terminations of the potentiometer being connected to respective signal connections and the wiper connection of the potentiometer being connected to one excitation supply terminal via a series resistor.
There is further provided a method of calibrating a weighing machine using a calibrating rig as above comprising the steps of:
1) Balancing the headwork with the weighing machine connected for normal operation;
2) Applying a known dead weight load and recording the reading on the headwork display;
3) Removing the load from the weighing machine;
4) Disconnecting the headwork from the load cell and connecting the calibration rig to the headwork;
5) Balancing the headwork by means of the potentiometer;
6) Applying weights to the load cell of the calibration rig until a reading close to the previous reading is obtained. The applied weight is the incremental weight and the reading represents the incremental reading;
7) Applying weights to the calibration rig load cell in steps of incremental weight to simulate an increase in readings in steps equal to the incremental reading on the headwork display;
8) Adjusting the headwork to achieve the correct reading;
9) Removing all weights from the calibration rig;
10) Disconnecting the calibration rig and reconnecting the weighing machine load cell to the headwork.
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Allen Peter G
Allen Steve R
GEC Avery Limited
Gibson Randy W.
Kirschstein et al.
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