JPS6141807B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a screw, a belt, a screw provided at the bottom of the hopper,
This invention relates to a quantitative discharge control method when discharging by an apron, vibration conveyor, etc., and is particularly suitable for quantitatively discharging muddy substances such as sludge.

To discharge the material in the hopper, a discharge mechanism such as a screw, a belt conveyor, or a vibrating feeder, which is usually installed at the bottom of the hopper, is used, but if the stored amount is small or the hopper height is low. In some cases, by simply setting the screw rotation speed, belt conveyor drive rotation speed, vibration feeder vibration motor rotation speed (frequency), etc., you can discharge a fixed amount without performing any other controls. I was able to do it.

However, as the hopper becomes larger or the height of the hopper becomes higher, the discharge amount fluctuates while the rotational speed of the discharge mechanism is fixed, making it difficult to discharge in a fixed quantity. In particular, it has been difficult to quantitatively discharge stored fluids such as sludge.

An example of conventional quantitative discharge control is shown in FIG. 1
is a hopper, which is equipped with a screw 2 at its bottom to transfer the stored material 3 and discharge it from an outlet 4. 5 is a conveyor scale which is designed to detect the amount of discharge. Reference numeral 6 denotes a rotation speed detection device for the screw 2, 7 a rotation speed increase/decrease device, 8 a discharge amount calculator, 9 a discharge amount indicating controller, and 10 a rotation speed indicating controller for the screw 2. In place of the conveyor scale 5, a hopper scale, an impact line flow meter, etc. may be used.

For control, a calculation element is detected by a conveyor scale 5, etc., the discharge amount is calculated by a discharge amount calculator 8, and compared with the set discharge amount, and based on the deviation, the rotation is controlled by a signal from a rotation speed indicating controller 10. A quantity increase/decrease device 7 is operated to change the rotational speed of the screw 2 (the driving rotational speed for a belt conveyor, the vibration frequency for a vibrating feeder) to perform quantitative discharge.

However, with this type of configuration, there are many problems such as adhesion to the conveyor scale 5, especially when the handled material has fluidity, resulting in significant errors in measuring the discharge amount, and stable quantitative discharge is not possible. It was difficult.

In order to prevent this, as shown in Fig. 2, a level detector 11 such as a load cell or a level meter that detects the level in the hopper 1 is used to detect a decrease in the amount stored in the hopper 1, and this decrease is calculated as the discharge amount. Some devices detect the discharge amount by differentiating it with a calculator 8, compare the set value and the calculated value, and control the rotational speed of the screw 2 based on the deviation.

However, this method is applicable only when the accumulated material is continuously fed into the hopper 1 without fluctuation using batch operation or a conveyor, and the amount of material being fed fluctuates or the material is fed intermittently. When this happens, the level of stored material fluctuates, making the calculation of the amount of discharge inaccurate and making it difficult to use.

It is an object of the present invention to provide a conveyor quantitative discharge control method that eliminates the above-mentioned drawbacks of the conventional method, compensates for fluctuations in the level of the hopper stored material, and performs stable and accurate quantitative discharge. This is the purpose.

In order to achieve this objective, the inventors conducted extensive research, and while conventional methods used to calculate conveyor emissions by assuming that they were simply proportional to the conveyor's rotation speed, the inventors focused on the fact that emissions are also related to the level of stored materials, and conducted research.
We confirmed that the pressure at the discharge port changes depending on the level of the stored material, and for example, when the level is high, the discharge amount increases compared to when it is low, even if the conveyor rotation speed is the same. This led to the present invention.

In other words, the calculated discharge amount calculated based on the conveyor rotation speed is further multiplied by a level-related correction coefficient, and the calculated discharge amount is regarded as the true detected value of the discharge amount, and the control is performed by comparing it with the set value. This is how it was done.

The present invention enables handling items stored in a hopper to
In the conveyor quantitative discharge control method for discharging a fixed amount by a conveyor provided at the bottom of the hopper, the level of the accumulated material in the hopper is directly or indirectly detected and a level signal is output, and the rotation speed of the conveyor is detected. outputs a rotation speed signal, and when calculating the discharge amount of the conveyor, a correction coefficient based on the level is added to the discharge amount calculated based on the rotation speed using the rotation speed signal, and a correction coefficient based on the level is added using the level signal. A corrected calculated discharge amount is obtained by multiplying the calculated discharge amount, the calculated discharge amount is compared with a set discharge amount, and the rotation speed of the conveyor is controlled based on the deviation to discharge a predetermined amount. This is a conveyor quantitative discharge control method.

Embodiments of the present invention will be described using the drawings. Third
In the figure, 11 is a level detector that detects the average level H of the stored material 3 in the hopper 1. As the detection end of the level detector 11, in addition to directly detecting the average level H using an appropriate level meter such as electrical, mechanical, optical, or acoustic, there is also a method of directly detecting the average level H using a hoppa scale, which detects the average level H. A method of calculating H and obtaining it indirectly is also used.

There is a relationship as shown in FIG. 4 between the discharge amount Q of the screw, which is a conveyor, and its rotation speed S.
In reality, there are cases where the relationship is like that, but to simplify the explanation, we will assume that it is a straight line. Let this relational expression be Q=αS...(1).

Next, when the screw rotation speed S is constant,
The relationship between the height H of the stored material 3 in the hopper and the discharge amount Q (Q/S=α) is as shown in FIG. The relational expression at this time is α=BH+A...(2), and the correction coefficient to correct the emission amount calculated based only on the rotation speed S in equation (1) is (1).
By multiplying the equation by this α, the calculated emission amount Q is obtained as follows.

Q=(BH+A)S...(3) This equation (3) is stored in the emission amount calculator 8.

The H value signal given from the level detector 11 and the S value signal given from the rotation speed detection device 6 are input to the emission amount calculator 8, and the equation (3) is calculated. The calculated discharge amount is compared with a set value, and the rotation speed S of the screw 2 is controlled based on the deviation, so that the discharge amount is controlled to match the set value.

The case where a screw is used as a conveyor has been explained above based on Fig. 3, but even if the conveyor is a belt conveyor or a vibration conveyor, the rotation speed of the belt drive unit or the rotation speed of the vibration motor can be changed as described above. You can control it like this.

In the case of a conveyor without a rotating part, such as an electromagnetic feeder, or a pneumatic or hydraulic vibration feeder, the vibration frequency may be controlled instead of the above-mentioned rotational speed.

The meaning of "rotation speed" described in the present invention also includes such "vibration frequency."

According to the present invention, the detection device does not come into contact with the stored material, eliminating the risk of accidents due to adhesion.Also, since the error in the discharge amount due to the level of the stored material in the hopper is corrected, even if the level fluctuation is large, the detection device can be adjusted accordingly. It is possible to provide a conveyor quantitative discharge control method that can stably control the discharge amount by performing calculations, and can have extremely great practical effects.

[Brief explanation of the drawing]

Figures 1 and 2 are flow diagrams of the conventional example, Figure 3 is a flow diagram of the embodiment of the present invention, Figure 4 is a graph showing the relationship between screw rotation speed and discharge amount, and Figure 5 is inside the hopper. It is a graph showing the relationship between storage level and discharge amount. 1...Hotsupa, 2...Screw, 3...Stored material, 4...Outlet, 5...Conveyor scale, 6...
...Rotation speed detection device, 7...Rotation speed increase/decrease device, 8...
...Emission amount calculator, 9...Emission amount indicating controller, 10
...Rotation speed indicating controller, 11...Level detector.

Claims (1)

[Claims] 1. In a conveyor quantitative discharge control method in which a conveyor provided at the bottom of the hopper discharges a fixed amount of material stored in a hopper, the level of the material stored in the hopper is directly or indirectly detected. When outputting a signal, detecting the number of revolutions of the conveyor and outputting a number of revolutions signal, and calculating the discharge amount of the conveyor, the number of revolutions is added to the discharge amount calculated based on the number of revolutions using the number of revolutions signal. A corrected calculated discharge amount is obtained by multiplying the level signal by a correction coefficient based on the level, the calculated discharge amount is compared with a set discharge amount, and the rotation speed of the conveyor is controlled based on the deviation. A method for controlling quantitative discharge of a conveyor, characterized in that discharge is performed in a fixed quantity.