JPH029697B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an automatic span adjustment method for a combination weigher.

The combination scale is equipped with a plurality of weighing hoppers, and weighs the object to be weighed supplied into each weighing hopper,
A set weight or a combination of weights close to the set weight is selected by calculating a combination of each measured value.

Conventional span adjustment of the combination scale described above involves first stopping the operation of the combination scale, then emptying all weighing hoppers, and then loading a reference weight to set the span constant, etc.

That is, since the span cannot be adjusted unless the operation of the combination scale is temporarily stopped, if the span changes during operation, accurate measurement cannot be performed and measurement accuracy deteriorates.

Therefore, since the span has to be adjusted at appropriate intervals during operation of the combination scale, the working efficiency of the combination scale has become extremely poor.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a method that can adjust the span while a combination weigher is in operation, thereby improving the work efficiency of the combination weigher and improving the combination accuracy. It is about increasing.

Such a span adjustment method for a combination weigher of the present invention is such that, in the combination weigher, a reference weight is timely loaded onto a weighing hopper that is not selected for combination during the combination work, and an output signal is generated when the reference weight is loaded and when the reference weight is not loaded. The feature is that the span constant is calculated from the difference between .

To explain an example of a combination scale using a drawing, reference numeral 1 in the figure is a dispersion plate made up of vertically long plates arranged adjacent to each other, and the objects to be weighed on the dispersion plate 1 are distributed so as to be conveyed in different directions. An electromagnetic vibration type feeder 9 is provided below the plate 1, and supply troughs 2 are arranged in a row on the outer side of the distribution plate 1.

The supply trough 2 is a conveyance path having a substantially U-shaped cross section, and is provided with an electromagnetic vibration type feeder 10 below, and a pool hopper 5 at the discharge end of each supply trough.

The pool hopper 5 includes a hopper body 5a and a bottom cover 5.
A hopper for storing objects to be weighed consisting of b.
A weighing hopper 6 is disposed below each pool hopper 5.

The measuring hopper 6 includes a hopper body 6a and a bottom lid 6b.
The scale body 12 is connected to the scale body 12 via the load cell 11.
It is provided in the hopper 6 to weigh the object to be weighed in the hopper 6.

The output of the load cell 11 of each weighing hopper 6 is inputted to the control device 4 via the A/D converter 13,
The control device calculates each measured value and selects a set weight or a combination close to the set weight by combining the measured values.

Each of the weighing hoppers 6 is provided with a platform 6c, and a reference weight x is suspended above the platform so as to be movable up and down.

The reference weight x is a weight with a known weight that serves as a reference for setting the span, and it moves up and down by turning on and off the solenoid 3, and when it moves down, it moves up and down on the platform 6c.
It is hereby incorporated by reference.

A memory 7 and a display section 8 are further connected to the control device 4.

Memory 7 stores the span constant of each load cell 11,
It stores the output count at the time of measurement and the output count when the reference weight x is loaded, and the display section 8 displays the number of the weighing hopper 6 selected as a combination, the combined weight, etc.

Of the ten weighing hoppers 6, four or less are usually selected in combination. The object to be weighed is discharged from the hopper 6' selected for the combination. Then, a new object to be weighed is carried into the empty weighing hopper 6' after the object to be weighed has been discharged, and after the carrying-in is completed, weighing is performed. For six or more weighing hoppers 6'' that are not selected as a combination, the selected weighing hopper 6' discharges the object to be weighed, brings in a new object to be weighed, and weighs the carried object to be weighed. It will be idle for a while.

The present invention is characterized in that span adjustment is performed during this idle state.

That is, the control device 4 drives the solenoid 3 of the weighing hopper 6'' that has not been selected as a combination to place the reference weight x on the platform 6c and adjust the span.

An example of span adjustment can be explained with reference to Fig. 3. b: Load cell output at no load a ₀ : Regular span constant X: Arbitrary load weight Y ₀ : Load cell output for load X at span constant a ₀ Before adjustment If the span constant of is normal, the weight is calculated by X = Y ₀ - b/a ₀ . However, when the span constant _a0 changes to a, the output of the load cell changes to Y, and in this case, the weight is calculated as follows: X=Y-b/a...(i).

If there is _{an object to be weighed in the hopper, X 1 : Weight of the} object to _{be weighed} in _the weighing hopper Load cell output a of ₂ : If the span constant after change is assumed, all values except a are known by mounting the reference weight X ₀ . The span constant a is the slope of the graph in FIG. Therefore, the span constant a after the change is calculated using the formula a= _Y2 - _Y1 / _X0 , and this span constant is stored in the memory 7 as a new span constant. Thereafter, span adjustment is performed by calculating the weight using the new span constant using the formula X=Y-b/a.

The steps of the span adjustment method described above will be explained with reference to FIG. 5. First, when the work starts, 21, the pool hopper 5 is opened and closed to carry the object to be weighed into the weighing hopper 6 (22), and weighed (23).

The weighing values are combined to calculate a combination that is close to the set weight 24, the weighing hopper 6 that provides the closest combination is selected 25, and the selected weighing hopper 6' is opened and closed to obtain the combination 26.

Zero point correction is performed for the weighing hopper 6'' that was not selected as a combination 27. This zero point correction is performed by determining whether or not the weighing value has changed after a predetermined time has elapsed, and if the weighing value has changed, It is assumed that the weight of the object to be weighed has not changed (as there is no change in the object to be weighed), but that the zero point has changed.
This is done by correcting the contents of the zero point register so that the measured value is equal to the previous measured value. Regarding this zero point correction method, the present applicant has published Japanese Patent Application No. 58-118727 (Japanese Unexamined Patent Publication No. 60-10400).
The detailed explanation will be omitted here.

After the above zero point correction, among the weighing hoppers 6'' that did not participate in the combination, one that meets the span adjustment conditions (single or multiple, etc.) is loaded with a reference weight 29, and the span is adjusted as described above. , remove the reference weight 31.

The above steps are repeated.

In the above embodiment, the weighing hoppers of the combination scale are arranged in two rows, but they may be arranged circumferentially as desired.

The span adjustment condition 27 is, for example, a condition in which a counter or the like is used to count the number of times that a combination is not selected and a predetermined number of times has been reached, or a timer is provided and the condition is that a predetermined time elapses.
Of course, it may be performed every time it is not selected.

As described above, the present invention includes a plurality of weighing hoppers, weighs the objects to be weighed supplied into each weighing hopper, calculates a combination of each weighed value, and calculates a set weight or a combination of weights close to the set weight. An automatic span adjustment method in which a reference weight is timely loaded on a weighing hopper that is not selected for the combination during combination work on the selected combination scale, and the span constant is calculated from the difference in output signal between when the reference weight is loaded and when the reference weight is not loaded. Therefore, the span of the weighing hopper can be adjusted without stopping the operation of the combination scale.

Therefore, since the span is adjusted while the combination scale is in operation, work efficiency is extremely high, and weighing accuracy and combination accuracy are also good.

By doing so, we will reach our intended purpose.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view showing a combination scale according to an embodiment of the present invention, Fig. 2 is a plan view thereof, Fig. 3 is a graph showing the principle of span adjustment, and Fig. 4 shows a combination scale according to an embodiment of the present invention. The block diagram and FIG. 5 are flowcharts showing the same operation. In the figure, 3...Solenoid, 4...Control device, 6
...Weighing hopper, 11...Load cell, x...
It is a reference weight.

Claims (1)

[Claims] 1. In a combination scale that is equipped with a plurality of weighing hoppers, weighs the objects to be weighed supplied into each weighing hopper, and calculates the combination of each weighed value to select a set weight or a combination of weights close to the set weight, An automatic span adjustment method in which a reference weight is loaded in a timely manner to a weighing hopper that is not selected as a combination during work, and the span constant is calculated from the difference in output signal between when the reference weight is loaded and when it is not loaded.