JPS6014183Y2 - hopper scale - Google Patents

Description

[Detailed description of the invention] The present invention relates to a hopper scale that repeatedly dispenses a fixed amount of objects to be weighed. To provide a hopper scale that automatically corrects the head difference between a supply hopper that supplies weighing objects to a weighing hopper and performs accurate quantitative dispensing.

Among the objects to be weighed, the apparent weight of powder and granular materials in particular changes depending on the surrounding environment (temperature, humidity), so in order to perform accurate quantitative dispensing, the correction value of the head difference must be calculated based on changes in the environment. It is necessary to make corrections accordingly.

However, with conventional hopper scales, the operator sets a predetermined head correction value to perform weighing, so it is extremely troublesome to perform weighing without frequently changing the head correction value, and it is difficult to accurately measure the weight. Quantitative dispensing was not easy to do.

Hereinafter, one embodiment of the hopper scale according to the present invention will be described based on the drawings.

Reference numeral 1 denotes a supply hopper, which has a gate 2 for opening and closing its bottom opening, and is driven by a drive device 3 such as a cylinder.

Reference numeral 4 denotes a weighing hopper provided below the bottom opening of the supply hopper 1, which has a weighing device 5 consisting of a load cell for weighing the object to be weighed discharged from the supply hopper 1, and a driving device 6 such as a cylinder. It has a gate 7 for opening and closing its bottom opening.

Reference numeral 8 denotes a quantitative setting section for setting a target weight value, which is set to supply a constant current to a potentiometer and output a reference voltage Vr corresponding to the target dispensing amount of - times.

A subtracter 9 inputs the output of the weighing device 5, which outputs the voltage Vg corresponding to the weight value of the heavy object received in the weighing hopper 4, as a subtractive number, and inputs the reference voltage Vr as the minuend; Outputs the potential difference.

10 is a comparator as a coincidence detection circuit, which saturates positively when the input voltage Vc is zero (V), and when it saturates positively, immediately closes the gate 2 to the drive device 3 and transfers the signal to the weighing hopper 4. The driver 6 is instructed to stop the supply of the objects to be weighed, and after the objects to be weighed floating in the head are completely supplied to the weighing hopper 4 via the delay circuit 11, the gate 7 is stopped. Command the release and make the payout take place.

Reference numeral 12 denotes an integrating circuit as an adder that cumulatively adds the potential difference, and is composed of an operational amplification WoP, a resistor R that determines the integration time, a capacitor C, etc. When the output of the comparator 10 is saturated, the switch SW1 of the input circuit is activated. It turns on and starts integrating the output signal of the subtracter 9, and the capacitor C halts the integrated value.

In addition, as means for correcting the drop with respect to the weight voltage Vg, a voltage obtained by adding the output voltage of the integrating circuit 12 and the output voltage of the subtracter 9 is set as the input terminal Vc of the comparator 10.

Further, once the drive circuit 6 opens the gate 2 by the output of the comparator 10, it keeps the gate 7 open until the payout is completed, regardless of the output state of the comparator 10.

Similarly, the drive circuit 3 closes the gate 2 until the weighing hopper 4 completes discharging.

At the start of operation, turn on switch SW2 to completely discharge the integrated voltage held by capacitor C, set the integrating circuit 12 output voltage Voot = Q (V), and set the comparator 10 input terminal Vc to the subtracter 9 output voltage. The so-called head correction is set to zero.

Here, the explanation will be made on the assumption that the set weight value is A (kg), and the voltage Vr corresponding to A (kg) is output to the quantitative setting section 8 output.

As the supply from the supply hopper 1 to the weighing hopper 4 progresses, the output voltage Vg of the weighing device 5 (FIG. 2a) changes to the reference voltage EE.
Vr, and the subtracter 9 output voltage approaches zero (V).

Time t when the amount supplied to weighing hopper 4 reaches A [kg]
1, the output voltage of the subtracter 9 becomes zero (■), and the comparator 10 (FIG. 2b) detecting this, instructs the drive device 3 to close the gate 2.

However, at this time, between the supply hopper 1 and the weighing hopper 4, there is a (
Since the object to be weighed (kg) is floating, when the object to be weighed existing at this head falls into the weighing hopper 4, at s2, the target set weight is set to a (kg).
This means that they received a greater supply of objects to be weighed.

Therefore, after a certain period of time T, the capacitor C that started integrating from time t2 is applied to the integrated voltage -Va (second Hold Figure C).

In the next measurement, the input terminal Vc of the comparator 10 is connected to the output voltage of the subtractor 9 and the integrated voltage of the output of the integrating circuit 12 -
Since the voltage value has changed to the sum of Akg and Va, the reference voltage Vr has changed from the voltage value corresponding to Akg to A(kg) a
This is equivalent to being corrected to a voltage value corresponding to (kg).

Therefore, the output state of the comparator 10 becomes positively saturated at the time when the amount of supply to the weighing hopper 4 reaches A (kg) a (kg), and it commands the drive device 3 to close the gate 2, thereby reducing the head. Time t when the floating object to be weighed completely falls
4, the head is automatically corrected so that the target set weight A (kg) is achieved.

In addition, even if the ambient environment changes and the object to be weighed in the head falls completely even though the head is corrected for akg, the amount supplied to the weighing hopper 4 may be lower than the target weight value.
(kg), a voltage corresponding to the deviation weight value +b (kg) is generated at the output of the subtractor 9, and the output voltage vOOT of the integrating circuit 12 becomes the hold voltage -Va and the deviation weight value b (kg). The voltage is automatically updated to -Va +Vb = -Vc, which is the sum of the corresponding integrated voltage +Vb.

Therefore, even if the surrounding environment changes, subsequent quantitative dispensing can be performed accurately.

In the above embodiment, the addition section that cumulatively adds the deviation weight value between the target weight value and the weight value of the object to be weighed immediately before dispensing supplied to the weighing hopper was explained as an analog circuit, but the addition section shown in FIG. The same is true even if it is configured with a digital circuit as shown in FIG.

In Fig. 3, 13 is a converter that converts the output signal of the weighing device 5 into a BCD signal, and 8' is a converter that converts the set target weight value into a BCD signal.
A setter that outputs a signal, 9' is a subtracter, inputs the output signal to the setter 8' as a minuend, inputs the output of the converter 13 as a subtractive, and outputs the calculation result as a BCD signal and a polarity signal P. .

Reference numeral 14 denotes a cumulative adder that cumulatively adds the calculation results of the subtracter 9' immediately before dispensing from the weighing hopper 4, and outputs the cumulative value as a head correction value.

15 is a subtracter to which the output signal of the subtracter 9' is inputted as the subtracted value, and the cumulative value of the cumulative adder 14 is inputted as the subtracted value; SW2;
' is a cumulative value reset switch of the cumulative adder 14.

16 is a NAND gate as a coincidence detection section, and subtracter 1
It is detected that the BCD signal of the 5 output becomes "0000" and the logic level becomes H? Flip to 1.

As explained above, according to the present invention, there is a weighing hopper that weighs the supplied object to be weighed, a supply hopper located above the weighing hopper that supplies the weighing object to the weighing hopper, and a supply hopper that supplies the weighing object to the weighing hopper. and a coincidence detection section that detects coincidence between the weight value of the object to be weighed and a preset target weight value and instructs the supply hopper to stop supplying the object to be weighed, and repeatedly dispenses the object to be weighed in a fixed amount. an adding section that cumulatively adds a deviation weight value between the target weight value and the weight value of the object to be weighed immediately before dispensing supplied to the weighing hopper; and a coincidence detecting section based on the cumulative value of the adding section. Since the system is equipped with a head correction means for correcting the target weight value for the feed hopper and the weighing hopper to automatically correct the head difference between the supply hopper and the weighing hopper, operability is significantly improved compared to the conventional method, and accurate quantitative dispensing is possible. .

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a hopper scale according to the present invention, FIG. 2 is a waveform diagram of essential parts of FIG. 1, and FIG. 3 is a schematic block diagram showing another embodiment. 1... Supply hopper, 4... Weighing hopper, 10... Comparator, 12...
・Integrator circuit.

Claims (1)

[Scope of utility model registration request] A weighing hopper that weighs the supplied object to be weighed, a supply hopper located above the weighing hopper that supplies the object to be weighed, and a preset weight value of the object to be weighed supplied to the weighing hopper. and a coincidence detection unit that detects coincidence with the target weight value and instructs the supply hopper to stop supplying the object to be weighed, and is configured to repeatedly dispense a fixed amount of the object to be weighed. an addition section that cumulatively adds the deviation weight value between the weight value of the object to be weighed and the weight value immediately before discharging the object supplied to the weighing hopper; and a head correction that corrects the target weight value to the coincidence detection section based on the cumulative value of the addition section. A hopper scale configured to automatically correct a head difference between a supply hopper and a weighing hopper.