JPH0158446B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adjusting the span (ratio) of a conveyor scale so that the measurement accuracy is not affected by changes in the state of the conveyor section or the like.

In general, a conveyor scale obtains an output signal that is proportional to the conveyance amount per unit length of the belt conveyor, and then accumulates the output signals to obtain the total conveyance amount.In this case, how much is this cumulative output signal? The ratio corresponding to the transported amount is called the span, and if the span is not changed due to changes in the condition of the conveyor, measurement accuracy may be affected. Therefore, conventionally, as shown in FIG. 1, a test chain 2 is provided on the belt conveyor 1 so that a predetermined mass M is applied per unit length, and the total belt length l of the belt conveyor 1 is measured. 1 is run an appropriate number of times to perform a span inspection, and the load cell 4 that detects the unit transportation amount of the belt conveyor 1 is adjusted so that the calculated total transportation amount Mln is displayed on the display 3. The span was adjusted by changing the amplification degree of the output signal by changing the value of a variable resistor 6 provided in the amplifier 5. Note that 7 is an A/D converter that converts the output signal of the amplifier 5 into a digital signal;
Reference numeral 8 denotes an accumulator, which accumulates the digital signal each time a pulse signal generated by the pulse generator 9 is supplied each time the belt conveyor 1 travels a unit length.

However, when span adjustment is performed by changing the amplification degree of the amplifier 5 in this way, the resolution is low and the adjustment is done visually, making it impossible to make accurate adjustments and requiring several adjustments. Time was running out. Furthermore, it is necessary to measure the entire length of the belt, which takes even more time when the belt is long.

An object of the present invention is to provide a span adjustment method that can shorten the time required for adjustment.

This invention will be explained below based on three embodiments shown in FIGS. 2 to 4. FIG. 2 shows a first embodiment. In this embodiment, the conveyor scale uses an amplifier 13 to amplify the output of a load cell 12 installed on a belt conveyor 10 to detect the transport amount per unit length, and then converts the output into a digital signal using an A/D converter 14. Each time the pulse signal generated by the pulse generator 16 is supplied to the accumulator 18 every time the pulse generator 10 travels a unit length, the accumulator 18 accumulates the digital signal, and the accumulated value is divided into the spans by the divider 20. The span value set in the value setter 22 is divided by, for example, 1000 and displayed on the display 24. Note that the reason why the total transportation amount is obtained by dividing the cumulative value by the span value is to improve the resolution and the measurement accuracy.

In such a conveyor scale, when performing span adjustment, a test chain 26 is provided on the conveyor 10 so that a predetermined weight W per unit length is applied to the conveyor 10. Then, measure the total length l of the belt of the belt conveyor 10, and
The number n of times the 0 is run is determined. Then, the transportation amount Wln obtained by calculation, for example, 50 kg is set in the span reference value setting device 28.

Then, the belt conveyor 10 is run n times to perform a span inspection. This produces an output of, for example, 48 kg in the divider 20, and 48 kg is displayed on the display 24. This output 48Kg and span reference value setter 28
The set value of 50Kg is supplied to the correction calculator, and the divider 32 in the correction calculator 30 divides it by 48÷50, and the divided value 0.96 is used as the span value setting in the multiplier 34. is multiplied by the span value of 1000 of the device 22 to determine a new span value of 960. Then, when the switch 36 is closed, a new span value 960 is set in the span value setter 22. Thereafter, the transport amount will be measured using the new span value.

The second embodiment shown in FIG. 3 differs in the conveyor scale for performing span adjustment according to the present invention, but the span adjustment method itself is the same as the first embodiment. That is, in the first embodiment, division by the span value is performed after accumulation, but in the second embodiment, division by the span value is performed before accumulation.

In the third embodiment, as shown in FIG.
8. Setter 40 for belt thickness t, setter 42 for rotation ratio r between belt conveyor 10 and pulse generator 16, setter 44 for test chain mass M, setter 46 for belt tension coefficient K, span A setter 48 for the total number of pulses P generated by the pulse generator 16 during inspection and a setter 50 for the number of slits N of the pulse generator 16 are provided, and the set value A of the span reference value setter 28 is used to measure the total length of the belt. It is designed so that you can obtain it without doing anything. Other configurations are similar to the second embodiment.

The reason why the set value of the span reference value setter 28 can be obtained from each of the above set values D, t, r, M, K, P, and N will be explained below.

If the mass per unit length of the test chain is M, the number of times the belt conveyor 10 runs during span inspection is n, and the total length of the belt conveyor 10 is L, then A
is A=M・L・n...(1). Also, the outer diameter of the pulley of the belt conveyor 10 is D, the thickness of the belt is t, and the pulley and pulse generator 1
6 is the rotation ratio with r, the total number of pulses from the pulse generator 16 during the span inspection is P, the belt tension coefficient determined from the experimental results is K, the rotation speed of the pulse generator 16 during the span inspection is NP, Pulse generator 16
Letting the number of slits be N, then P=N・Np...(2) Np=nL/π(D+t)K×r...(3) From equations (2) and (3), n=π(D+t)・P・K/L・r・N…
…(4) becomes. From formulas (1) and (4), A=M・π・(D+t)・P・K/r・N ...(5). Therefore, set D, t, r, M, K, P, and N in each of the setting devices 38 to 50, respectively,
If the span reference value setter 28 is configured to perform the calculation of equation (5), the span can be corrected without measuring the entire length of the belt. Incidentally, the total number of pulses P is determined by the start pulse number provided on the belt conveyor 10.
By inputting a signal output from a device 52 for detecting a stop mark 50 (for example, a magnet) to a preset counter 54 set to n, a start signal 5 is input to a counter 56 for counting pulse signals.
7, obtained by supplying the stop signal 58.

As described above, according to the present invention, since span correction is performed on the output of the load cell 12 or the digital signal converted into a digital signal, the resolution is high and the span value can be completely corrected in one span inspection. , the time required for adjustment can be shortened. Furthermore, as in the third embodiment, the outer diameter of the pulley,
By setting the belt thickness t, rotation ratio r, test chain mass M, belt tension coefficient K, total number of pulses during span inspection P, and number of slits N in the pulse generator, the total length L of the belt can be measured. Since the true total transportation amount can be obtained by calculation without having to do so, the time required for span adjustment can be further reduced.

In the third embodiment, the divider 20 is provided on the input side of the accumulator 18, but it may be provided on the output side of the accumulator 18 as in the first embodiment. Furthermore, although the test chain 26 was used in each embodiment, a test weight may also be used.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conveyor scale in which a conventional span adjustment method is implemented, Figure 2 is a block diagram of a conveyor scale in which a first embodiment of the span adjustment method according to the present invention is implemented, and Figure 3 is the same. FIG. 4 is a block diagram of a conveyor scale in which the second embodiment is implemented, and FIG. 4 is a block diagram of a conveyor scale in which the third embodiment is implemented. 10... Belt conveyor, 12... Load cell, 14... A/D converter, 16... Pulse generator, 18... Accumulator, 20... Divider, 22...
Span value setter, 30...Correction calculator, 38 to 50...Setter.

Claims (1)

[Claims] 1. Converting the analog output of a load detector provided on the belt conveyor into a digital signal, and converting the digital signal based on a pulse signal generated by a pulse generator every time the belt conveyor travels a unit length. In a conveyor scale that calculates the transport amount by accumulating and dividing by a predetermined span value, or by accumulating the above digital signal divided by the above span value; a predetermined weight is applied per unit length of the belt conveyor. A process in which a test chain or a test weight is installed on the belt conveyor and the belt conveyor is run a predetermined number of times; A method for adjusting the span of a conveyor scale, which comprises the steps of determining the ratio of amounts and correcting the span value based on this ratio. 2. Converting the analog output of the load detector provided on the belt conveyor into a digital signal, and accumulating and predetermining the digital signal based on the pulse signal generated by the pulse generator every time the belt conveyor travels a unit length. In a conveyor scale that calculates the transport amount by dividing the above digital signal by the span value or by accumulating the above digital signal divided by the above span value; A process of installing a weight on the belt conveyor and causing it to travel a predetermined number of times, the predetermined weight, the outer diameter of the pulley of the belt conveyor, the thickness of the belt, the total number of pulse signals generated by the pulse generator during the travel process,
The ratio of the transport volume obtained during the traveling process to the standard transport volume calculated from the number of slits in the pulse generator, the rotation ratio between the pulley and the pulse generator, and the tension coefficient of the belt is determined, and based on this ratio, A method for adjusting the span of a conveyor scale, which comprises the process of correcting the above-mentioned span value.