JPS6153649B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zero point adjustment device for a belt scale configured to continuously integrate instantaneous weight over a working length to display the total transport amount.

With belt scales, weighing is carried out via an endless belt-like body (hereinafter referred to as a belt) that conveys the object to be weighed, so if the belt thickness is uneven or there are deposits on the belt, This acts as an error component in the instantaneous weight measurement, making it impossible to obtain an accurate total transportation amount. The zero point adjustment device is provided to remove the influence of the above-mentioned error component on the total transportation amount display, and the integrated value of the total transportation amount becomes zero during empty operation when no conveyed objects are placed on the belt. Thus, the instantaneous weight value is corrected by the average value of the zero point deviation and then integrated. In order to obtain an accurate total transportation amount, it is desirable to correct the instantaneous weight value using the latest average value of the zero point deviations, but in the conventional zero point adjustment device, the operator first adjusts the The feeder placed in is placed in a supply stop state,
After that, in order to confirm that the belt scale has entered unloaded operation, and calculate the average value of the zero point deviation,
The operator instructs the start of the detection operation,
Performing the zero point shift detection operation frequently not only reduces the efficiency of transporting objects to be weighed to a production line, etc., but also requires a worker to be permanently present, resulting in poor workability.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide an automatic zero point adjustment device that can contribute to accurate calculation of the total transport amount without causing a decrease in work efficiency. .

An embodiment of the present invention will be described below based on the drawings. Reference numeral 1 designates a screw feeder disposed before the belt scale 2, which inputs a supply control signal a from a production line, etc. after the belt scale 2, and controls the operation of the motor 1a with a control circuit 1b. The raw material cut-out is controlled on-off. Reference numeral 3 denotes a load conversion unit that measures the instantaneous weight of a working length section via the belt 2a, and includes a carrier roller 3a that supports the belt 2a on the outward journey from below, a load cell 3b that converts the vertical movement of the roller 3a into an analog signal, and a roller. 3a and a load cell 3b. Reference numeral 4 denotes a pulse transmitter, whose rotating shaft is connected to an idling roller 4a in contact with the dual-path belt 2a, and outputs a pulse train signal P corresponding to the conveyance speed of the belt 2a. Reference numeral 5 denotes a totalizer, and a correction unit ₅ outputs a weight signal G1 by correcting the load cell 3b output signal _G0 , which is a signal to be corrected, using a pre-calculated average value of zero point deviation as a correction value J.
a, and an analog/digital converter 5b that digitally converts the load cell 3b output via the correction unit 5a.
, a multiplier 5c that calculates the instantaneous transport amount from the weight signal output from the analog-to-digital converter 5b and the speed signal of the pulse transmitter 4, an adder 5d that accumulates the instantaneous transport amount, and a preset zero point. It is comprised of a comparison section 5e that compares the nearby weight g and the instantaneous weight calculated by the correction section 5a. Comparison part 5
If the instantaneous weight generated in the output of the correction unit 5a exceeds the weight g, it is determined that the belt 2a is conveying the raw material, and no signal is output to the subsequent stage, and the weight g exceeds the weight g. When the instantaneous weight generated in the output of the correction section 5a is less than , it is determined that the belt 2a is not conveying the raw material, and an empty load signal H is output. 6 is a transportation amount display device,
The cumulative value data D calculated by the adding section 5d is digitally displayed as a weight value. 7 is an AND gate that detects a state in which both the supply stop signal S output by the control circuit 1b and the empty load signal H of the totalizer 5 are output during the cut-out stop period of the feeder 1.
Reference numeral 8 denotes a zero point adjustment device, which is instructed to start updating the correction value J when the supply stop signal S and the empty load signal H are outputted by the AND gate 7 output, and the pulse transmitter 4 starts the belt adjustment. If the number of pulses generated in one rotation of 2a is M (where M is a positive integer), then the number of pulses generated during n rotations of the belt 2a, that is, n・M
During the update operation until the output of the pulse signal of Even if the supply control signal a is input to the control circuit 1b, a supply prohibition signal R is output to the control circuit 1b to prohibit raw material cutting from the feeder 1, and during the update operation, the instantaneous transport amount of the analog-to-digital converter 5b output is If A is the integrated value and B is the number of sections of the working length of the load converter 3 with respect to the entire circumference of the belt 2a, then the average value C of the latest zero point deviation is calculated by C=A/n・B. is calculated and written as the correction value J. Note that the updated correction value J is stored until the time when the AND gate 7 detects coincidence again and is output to the correction section 5a.

With this configuration, the empty load signal H is output from the totalizer 5 until the feeding of the feeder 1 is temporarily stopped by the supply control signal a from the production line or the like after the belt scale 2 and restarted. When the correction value J input to the correction unit 5a is output, an operation for calculating the average value of the zero point deviation is started, and when the calculation operation is completed, the feeder 1
Since the raw material is cut out again according to the instruction of the supply control signal a, there is no need for the operator to instruct the operation of calculating the average value of the zero point deviation.

In the above embodiment, the operation for calculating the average value of the zero point deviation is given priority over the supply control signal a, and the raw material cutting out of the feeder 1 is prohibited until the calculation is completed. The same holds true even if priority is given over arithmetic operations. In this case, if the supply control signal a is input during the calculation, the calculation is stopped, the output of the load cell 3b is corrected with the correction value immediately before the calculation started, and the transportation amount integration operation is performed again. Therefore, accurate total transportation volume can be obtained without compromising production line efficiency.

Furthermore, in the above embodiment, the correction unit 5a is configured to pass the output signal of the load cell 3b during the calculation of the zero point adjustment device 8, but during the calculation, the correction unit 5a corrects the output signal of the load cell 3b using the average value of the previous zero point deviation. The same effect can be obtained by configuring the system to do this and sequentially correcting the average value of the previous zero point deviation based on the calculation result.

In addition, in the above embodiment, the feeder 1 in the previous stage
Although the screw feeder has been described, the same applies even if the feeder is directly cut out from the hopper and the opening/closing signal of the supply gate is configured as the supply stop signal S.

As explained above, the automatic zero point adjustment device for the belt scale of the present invention is provided at the feeder which is disposed in the front stage of the belt scale so as to supply the object to be weighed to the belt scale, and whose supply and supply stop are instructed by an external supply control signal. and a comparison unit that detects the empty state of the belt scale by comparing the weight signal after zero point correction, which is obtained by correcting the belt scale instantaneous weight value with the stored average value of the zero point deviation, and a preset weight near the zero point. , an AND gate that detects a state in which the feeder is not supplying and the comparison section is detecting an empty load, and updating the average value of the zero point deviation based on the instantaneous weighing value from the time when this AND gate detects a match. During the update process, a zero point adjustment device is installed that prohibits the feeder from supplying the object to be weighed to the belt scale, regardless of the external supply control signal, so the operator cannot force the feeder in front of the belt scale. There is no need to perform the above-mentioned detection operation in a state where the supply is temporarily stopped, and there is no need for an operator to be constantly present for zero point adjustment.

Further, the automatic zero point adjustment device for a belt scale of the present invention includes a feeder which is disposed at the front stage of the belt scale so as to supply the object to be measured to the belt scale, and whose supply and supply stop are instructed by an external supply control signal; a comparison unit that detects an empty state of the belt scale by comparing the weight signal after zero point correction, which is obtained by correcting the scale instantaneous weight value with the average value of the stored zero point deviation, and a preset weight near the zero point; an AND gate that detects a state in which the feeder is stopping supply and the comparison unit is detecting an empty load;
From the time this AND gate detects a match, the average value of the zero point deviation is updated based on the instantaneous weighing value, and before the end of this update process, the external supply control signal is used to update the belt scale by the feeder. If the belt scale is equipped with a zero point adjustment device that finishes the update process when the supply of the object to be measured is instructed and instructs the zero point correction using the average value of the zero point deviation stored immediately before the start of the update process. It is possible to obtain an accurate total transportation amount without impairing the efficiency of the interposed production line.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a block diagram of a belt scale weighing conveyor system equipped with an automatic zero point adjustment device, and FIG. 2 is a block diagram of the main parts of FIG. 1. 1... Screw feeder, 2... Belt scale, 3b... Load cell, 4... Pulse transmitter, 5... Totalizer, 5e... Comparison unit, 6... Total transportation amount display device, 7... AND gate, 8... Zero point adjustment device, a... Supply control signal [external supply control signal], H... Empty signal, J... Correction value, R... Supply prohibition signal, S... Supply stop signal.

Claims (1)

[Scope of Claims] 1. A feeder which is disposed in front of the belt scale so as to supply the object to be measured to the belt scale, and whose supply and supply stop are instructed by an external supply control signal;
a comparison unit that detects an empty state of the belt scale by comparing the weight signal after zero point correction, which is obtained by correcting the belt scale instantaneous weight value with the stored average value of the zero point deviation, and a preset weight near the zero point; an AND gate that detects a state in which the feeder is stopping supply and the comparison section is detecting an empty load; and from the time this AND gate detects a match, the average value of the zero point deviation is updated based on the instantaneous weighing value. Run,
An automatic zero point adjustment device for a belt scale, comprising: a zero point adjustment device that prohibits the feeder from supplying the object to be measured to the belt scale regardless of an external supply control signal during an update process. 2. A feeder which is disposed in front of the belt scale to supply the object to be measured to the belt scale, and whose supply and supply stop are instructed by an external supply control signal;
a comparison unit that detects an empty state of the belt scale by comparing the weight signal after zero point correction, which is obtained by correcting the belt scale instantaneous weight value with the stored average value of the zero point deviation, and a preset weight near the zero point; an AND gate that detects a state in which the feeder is stopping supply and the comparison section is detecting an empty load; and from the time this AND gate detects a match, the average value of the zero point deviation is updated based on the instantaneous weighing value. When the feeder is instructed to supply the object to be weighed to the belt scale by the external supply control signal before the update process ends, the update process is finished and the zero point stored immediately before the start of the update process is executed. An automatic zero point adjustment device for a belt scale, which is provided with a zero point adjustment device that instructs zero point correction based on the average value of deviation.