JPS641730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic metering and feeding device that measures powdery raw materials and then supplies them to other processing equipment.

Automatic metering and feeding equipment automatically measures and supplies powder and granular raw materials, etc., and occupies an important position in the production line of factories that handle many types of powder and granular raw materials. ing. This type of automatic metering and feeding apparatus generally weighs powder and granular material supplied from a storage hopper with a weighing hopper, and supplies the powder and granular material from this weighing hopper to other processing equipment. in this case,
There is a feeding metering method that controls the input amount into the weighing hopper so that it becomes a predetermined measurement setting value, and another method that controls the input amount into the weighing hopper in advance so that the amount discharged from the weighing hopper becomes the measurement setting value. There is a discharge metering method. FIG. 1 is a diagram showing the state of the weighing hopper during these measurements, in which A shows the state inside the weighing hopper when the input weighing method is used, and B shows the state inside the weighing hopper when the discharge weighing method is used. In Figure A, considering the state when the powder or granular material is introduced, the amount of the powder or granular material in the weighing hopper gradually increases as it is introduced from the storage hopper. When the input target value A is reached, a closing command is sent to the storage hopper. The input target value A is the head correction value ε from the measurement setting value A ₀ .
The head correction value ε is a value determined in consideration of the amount of powder and granular material flowing into the weighing hopper after the storage hopper closing command is issued.
In other words, there is a response delay and operation time of the control system and mechanical system from when a storage hopper closing command is issued until the storage hopper actually closes, and even after the storage hopper is actually closed, there is a delay in the exit of the storage hopper. Since some powder and granules still remain between the storage hopper and the weighing hopper, the powder still flows into the weighing hopper even after the storage hopper blockage command is issued, and the target input value A is reached.
It is thought that the supply to the weighing hopper will stop at a point where the head correction value ε is greater than . Therefore, the input target value A is set in advance to be less than the metering set value A ₀ by the head correction value ε. However, even if this is done, the actual input amount G will deviate from the measurement setting value _A0 . The measurement error δ is the value obtained by subtracting the measurement setting value A ₀ from the actual input amount G, and can take a positive or negative value depending on the value of the actual input amount G (positive in the case of the figure).

Next, in the discharge metering method shown in FIG. At this time, a discharge stop command is issued when the powder and granular material in the weighing hopper has been discharged by the discharge target value A, and when the actual discharge amount G is reached, the actual discharge is stopped. In this case as well, the emission target value A
is determined as the value obtained by subtracting the head correction value ε from the measurement setting value A ₀ , and the measurement error δ is determined as the value obtained by subtracting the measurement setting value A ₀ from the actual discharge amount G.
In this way, in the automatic metering and feeding device, the value of the actual input amount (actual discharge amount) G is adjusted from the metering setting value A ₀ to the head correction value ε so that it becomes equal to the metering setting value A ₀ .
is subtracted to determine input (discharge) target value A, and metering control is performed based on this. In the conventional automatic metering and feeding device, the head correction value ε
was set by the operator by changing the value depending on the situation of measurement error.

By the way, this head correction value ε depends on the characteristics of the device,
It varies slightly depending on the physical properties of the object to be measured, the measurement setting values, etc., and it is extremely difficult to determine the optimum value by obtaining data, and therefore there is a certain limit to the measurement accuracy.

In view of the above-mentioned circumstances, the present invention provides an automatic metering and feeding device that can measure with high accuracy by automatically correcting the head correction value. , the present invention subtracts the measurement setting value from the actual input amount or actual discharge amount at the previous measurement to obtain the previous measurement error, and if the absolute value of this measurement error is larger than the predetermined dead band setting value, this measurement The error is multiplied by a predetermined constant, and the current head correction value is calculated based on this value and the previous head correction value. If the weighing error is less than the dead zone setting value, the previous head correction value is calculated. It is characterized in that the current head difference correction value is used as it is.

Embodiments of the present invention will be described below based on the drawings. FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, in which 1 is a storage hopper in which powder and granular material 2 is stored, and 3 is a storage hopper located close to the lower end opening of the storage hopper 1. This is an electromagnetic feeder installed at The electromagnetic feeder 3 is controlled to be driven or not driven by a comparison control circuit 5, and when it is driven, it vibrates and conveys the powder 2 and feeds it into the upper opening of the weighing hopper 6 at high or low speed. Arms 7a and 7b that extend in the horizontal direction are provided opposite to each other on the upper outer peripheral surface of the weighing hopper 6, and these arms 7a and 7b are respectively attached to fixed ends via load cells 8a and 8b and wires. In this case, the weighing hopper 6 is suspended from the fixed end via the load cells 8a, 8b. Reference numeral 9 denotes an electromagnetic feeder provided close to the lower end opening of the weighing hopper 6, and is controlled by the comparison control circuit 5 similarly to the electromagnetic feeder 3. 10 is a weight detection circuit, which detects the weight of the powder or granular material 2 in the weighing hopper 6 based on the weight signals output by the load cells 8a and 8b;
The input (or discharge in the case of the discharge metering method) amount W _R is supplied to the comparison control circuit 5, and the actual input (discharge) amount G _o at the end of the input (discharge) is supplied to the CPU 12, which will be described later. Reference numeral 11 denotes an operation unit consisting of a keyboard, etc., which controls the measurement setting value A ₀ , the initial value ε ₀ of the head correction value,
It is provided for inputting a constant K and a dead zone setting value D. This initial value ε ₀ is a head correction value used during the first measurement, and may be zero. Also,
The constant K is an empirically determined value, and the granular material 2
It varies depending on the type etc. Further, the dead zone setting value D indicates the allowable range of the measurement error δ _o , and examples thereof are shown in FIGS. 3 and 4. 12 is a central processing unit (CPU), which in addition to controlling each part of the device,
The computation described later is performed, and the input (discharge) target value _Ao , which is the computation result, is supplied to the comparison control circuit 5. The comparison control circuit 5 then compares the input (discharge) amount W _R with the input (discharge) target value A _o , and if A _o > W _R , drives the electromagnetic feeder 3 and controls the electromagnetic feeder 9
When A _o =W _R , the electromagnetic feeder 3 is stopped and the electromagnetic feeder 9 is driven. Also, 14 is
A memory 15 stores programs used by the CPU 12, and a data bus.

Next, the operation of this embodiment will be explained with reference to FIGS. 2 and 3. FIG _. 3 is a diagram showing the weight change in the weighing hopper 6 when the powder or granular material 2 is repeatedly weighed by the input weighing method. is input. Also, A _o , G _o , ε _o , δ _o (n=1, 2, 3,
4) are the nth measurement target value, actual input amount,
Indicates head correction value and weighing error.

Now, when starting measurement, the operator first operates the operation unit 11 to input the measurement setting value A ₀ , the initial value ε ₀ of the head correction value ε, and the constant K to the CPU 12,
Next, start weighing. This will cause the CPU
12 is the first input target value shown in Figure 3 A.
A ₁ is calculated using the following equation and is supplied to the comparison control circuit 5.

A ₁ = A ₀ −ε ₁ ...(1) However, ε ₁ = ε ₀ By the way, in the initial state, the weighing hopper 6
is empty and input amount W _R = 0, so A ₁ > W _R
becomes. Therefore, the comparison control circuit 5 starts driving the electromagnetic feeder 3 and starts to drive the powder and granular material in the storage hopper 1.
is thrown into the weighing hopper 6 at high speed. In this way, the powder or granular material 2 is charged into the weighing hopper 6, and the input amount W _R is set to a predetermined value (A ₀ in Fig. 3).
-S), the comparison control circuit 5 controls the electromagnetic feeder 9, switches the feeding speed to a low speed, and prepares for the end of feeding. When W _R =A ₁ , the comparison control circuit 5 issues a storage hopper closing command to the electromagnetic feeder 3 to stop the electromagnetic feeder 3. At this time, it takes some time after the command is issued until the feeding into the weighing hopper 6 actually stops, and during this time the amount fed into the weighing hopper 6 is G1 in Figure 3 A.
increase to. When the first feeding is completed in this manner, the comparison control circuit 5 drives the electromagnetic feeder 9 to discharge the powder 2 from the weighing hopper 6. Then, the CPU 12 reads the actual input amount G ₁ from the weight detector 10 and calculates the second input target value A ₂ as follows.

The previous (first) weighing error δ ₁ is determined by the formula δ ₁ = G ₁ −A ₀ ……(2), and then the absolute value of the weighing error δ ₁ |δ ₁ | is |δ ₁ |≦D (3) (where D is the dead zone setting value) If the following formula is satisfied, the previous head difference correction value ε ₁ is used as the current head difference correction value ε ₂ . In other words, ε ₂ = ε ₁ ...(4). On the other hand, if the absolute value |δ ₁ | satisfies the formula |δ ₁ |>D ...(5), the previous head correction value ε ₁ is corrected by the following equation, and the current head correction value ε ₂ get. That is, according to the formula ε ₂ = ε ₁ + Kδ ₁ ...(6), the current head correction is made by adding the product of the previous weighing error δ ₁ and the constant K to the previous head correction value ε ₁ . We get the value ε ₂ . In this way, the head correction value ε ₂ obtained by equation (4) or (6) is subtracted from the measurement setting value A ₀ to obtain the second injection target value A ₂ . That is,
The CPU 12 calculates the input target value A ₂ using the formula A ₂ =A ₀ −ε ₂ (7), and supplies this value to the comparison control circuit 5. In this way, the second weighing shown in FIG. 3B is performed in the same manner as the first one.

In this way, when the (n-1)th measurement is completed, the CPU 12 performs the nth measurement as follows.
Find the target input value _Ao for the first time.

δ(n-1)=G(n-1)-A ₀ ...(8) ε _o =ε(n-1)...(9) (However, when |δ(n-1)|≦D) ε _o = ε(n-1)+Kδ(n-1) ...(10) (when |δ(n-1)|>D) These equations are equations (2), (4), This corresponds to equation (6), and an example of its application will be explained based on FIG. In Figure 3 A (first measurement) and B (second measurement), |δ ₁ |>D, |δ ₂ |>D, so from formula (10), the head correction values ε ₂ , ε ₃ As a result, ε ₁ < ε ₂ < ε ₃ . Then, in the third measurement (FIG. 3C), |δ ₃ |<D, and the absolute value |δ ₃ | of the measurement error δ ₃ becomes smaller than the dead zone setting value D. This is because the third measurement was carried out extremely accurately, and the fourth measurement (see figure d)
In this case, it is considered that there is no need to modify the head correction value ε ₄ . Therefore, ε ₄ =ε ₃ is set using equation (9), and the fourth measurement is performed based on this.
In this way, if the previous weighing was performed extremely accurately, the hunting phenomenon during weighing can be prevented by performing the current weighing under the same conditions as the previous time. Weighing accuracy can be further improved.

To summarize the above, the previous actual input amount G(n-1)
Find the previous weighing error δ(n-1) by subtracting the weighing set value A ₀ from and calculate its absolute value |δ(n-1)|
is less than the dead zone setting value D, the previous head correction value ε(n-1) is changed to the current head correction value ε _o (=
ε(n-1)), and if the absolute value |δ(n-1)| is larger than the dead zone setting value D, the weighing error δ(n-1)
and a constant K, and add the previous head correction value ε(n-1) to that value to obtain the current head correction value ε _o . In this way, if the previous measurement was performed with an accuracy within the set range, the measurement will continue as it is, and if the previous measurement was not performed with the accuracy within the set range,
Automatically correct the head correction value _εo . In this way, the value of the head correction value ε _o can be gradually brought to an optimal value.

Next, FIG. 4 is a diagram showing the weight change in the weighing hopper 6 when weighing is repeated by the discharge weighing method. In the figure, W _o (n=1, 2, 3, 4) is This is the weight of the powder or granular material 2 that has been appropriately charged into the weighing hopper 6 in advance, and the weighing is performed based on this weight W _o . The specific method is almost the same as the input metering method described above, so its explanation will be omitted.

As explained above, the present invention subtracts the measurement setting value from the actual input amount or actual output amount at the previous measurement to obtain the previous measurement error, and the absolute value of this measurement error is calculated from the predetermined dead band setting value. If the weighing error is also large, this weighing error is multiplied by a predetermined constant, and the current head compensation value is calculated based on this value and the previous head compensation value. If the weighing error is less than the dead zone setting value, Since the previous head correction value is used as the current head correction value, the head correction value is automatically corrected, thereby improving the metering accuracy of the automatic metering and feeding device. Further, by providing the dead zone, it is possible to prevent the hunting phenomenon that occurs in each weighing batch, thereby further improving the weighing accuracy.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the state of the weighing hopper during measurement, Fig. 2 is a block diagram showing the configuration of an embodiment of the present invention, and Fig. 3 is a diagram showing repeated weighing of powder and granular material using the input weighing method. FIG. 4 is a diagram showing the weight change in the weighing hopper 6 when weighing powder or granules is repeated by the discharge weighing method. 2... Powder (object to be weighed), 6... Weighing hopper,
12... CPU (calculation means), A ₀ ... Weighing set value,
A _o ...(n=1,2...)...Input (discharge) target value, D...Dead band setting value, G _o (n=1,2...)...
...actual input amount (actual output amount), K...constant, ε _o (n=
1, 2...)...Head correction value, δ _o (n=1, 2...)
...Weighing error.

Claims (1)

[Scope of Claims] 1. In an automatic metering and supplying device that determines a target input value or a target discharge value based on a metering set value and a head correction value, and performs automatic metering based on this target value, the metering set value is input. input means for inputting a predetermined constant; input means for inputting a dead zone set value; If the absolute value of this weighing error is less than the dead band setting value, the previous head correction value is used as the current head correction value, and if the absolute value of the weighing error is greater than the dead band setting value, the An automatic metering/feeding device comprising a calculation means for multiplying the error by the constant and calculating a current head correction value based on this value and a previous head correction value.