JPS5943732A - Control method for constant feed ware - Google Patents

Abstract

PURPOSE:To improve accuracy of discharging a specified quantity of flow by a method wherein a control signal of a discharging device is controlled in such a way as discharging capability is set to a certain constant in response to the weight of the discharged item in a weighing hopper. CONSTITUTION:For example, when the first screw feeder is to be controlled, CPU11 at first checks if the operation is in its suplying period, and when the operation is in the discharging period, the updated weight is read from A/D converter 10 and a discharging quantity of feeder per unit time is calculated in reference to a difference between the updated weight and previously read the former weight and then the value is compared with the desired flow rate F. A control signal for a motor 6 is varied through a motor control circuit 5 in such a way as the actual discharging quantity approaches the desired flow rate F and then the newest read weight is checked if it coincides with the predetermined value and the lower limit setting value WL. When the coincidence is detected, the control signal for the motor 6 is stored in the addresses A, B and C in the memory 12. In this way, a control signal for the motor 16 is changed over in response to the weight and a variation in flow rate in the supplying period is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a constant meteor ware that constantly discharges meteors.

Conventionally, constant feed/doware is weighed by a weighing device (1
), a weighing hopper (2), for example a first screw feeder (3) mounted as a discharge device at the bottom of this weighing hopper (2);
A second screw feeder (4) supplies the discharged material to the hopper (2), and a second screw feeder (4) supplies the material to be discharged to the hopper (2), and a second screw feeder (4) supplies the material to be discharged to the first screw feeder (4) via the motor control device (5) based on the weighing signal from the weighing device (1). Motor (6) (7) of second screw feeder (3) (4)
) and a control device main body (8). Then, the control device main body (8) has a weighing potper (2).
The weight W of the discharged material in the
~ lower limit set value wl, the supply from the second screw feeder (4) to the weighing hopper (2) is stopped and the weighing device! <1) Output to the motor control device (5) so that the reduced weight per unit time of the weight W determined from <1) becomes a set constant discharge amount or so that the total discharge weight from the start of discharge approaches the target value. The motor (6) of the first screw feeder (3) is
) is controlled 1:'Hereinafter, this period will be referred to as the discharge period (H)]. However, from time 114 shown below
During period 1o, the accurate discharge amount per unit time cannot be determined from the weight signal of the weighing device (1), so the control based on the decreasing change in the weight signal of the first screw feeder (3) is The process is temporarily interrupted at time tL. The weight W is the lower limit set value Wl,
At [time [1,]], the control device main body (8) moves from the second screw feeder (4) to the weighing hopper (2).
The second screw feeder (4) is started to be driven via the motor control device (5) so that replenishment is carried out at a substantially constant flow rate. This state continues until the time Un when the weight W reaches the upper limit set value wU, and after the completion of replenishment, the first
The control state of the screw feeder (3) is also returned to the original state.

Note that from time tI to t. Because flow rate control cannot be performed during the replenishment period (I) until the replenishment period (I) due to the reasons mentioned above, the conventional control device main body (8) controls the motor to maintain an appropriate discharge flow rate during the replenishment period (I). The motor (6) of the first screw feeder (3) is controlled via the control device (5).
), for example, at time t while maintaining the driving state at time t□4. Configured to drive up to.

Therefore, the accuracy of the discharge flow rate during the replenishment period (1) is
■It is worse than 1), from the discharge period (11) to the replenishment period (
At present, the accuracy of the discharge stream 1 over 1) is worse than that of the discharge period.

The present invention has been made by focusing on the fact that there is a nearly constant tendency between the weight of the material to be discharged in the weighing hopper and the discharge capacity of the discharging device attached to the weighing hopper. Until the weight of the discharged material reaches the lower limit set value, the control signal to the discharge device is controlled so that the discharged material is discharged in a constant flow from the total 1 hopper according to the decrease in the mold f1, and this discharge is During the period, a plurality of control signals are stored corresponding to the weight level, and when the weight falls to the lower limit set value, an almost constant amount of the discharged material is replenished to the weighing hopper until the upper limit set value is reached. and during this replenishment period, the past control signals stored in advance are sequentially read out according to the weight level of the discharged material in the weighing hopper and output to the discharge device.

Hereinafter, a specific embodiment of the present invention will be described based on FIGS. 8 to 6.

Figure 8 shows the weight of the discharged material in the 4-hole hopper (2) ff1w
The relationship between the discharge capacity of the first screw feeder (3) and the discharge capacity of the first screw feeder (3) was measured for eight raw materials (a), (b), and (c), and the rotational speed of the motor (6) was constant. As can be seen from FIG. 8, the discharge capacity of all of the eight raw materials (a), (b), and (c) tends to improve as the weight jtw increases. Therefore, if the motor (6) is rotated in the driving state at time t□ as in the conventional case, the replenishment period (
In I), the flow rate tends to gradually increase, and the overall control accuracy deteriorates.

FIG. 4 shows an example of the control method of the present invention. Here, the same predetermined setting values W1 and w2 of the upper limit setting value WU and lower limit setting value wL are set, and during the replenishment period (1), the motor (6) of the first screw feeder (3) is controlled. That is, the period J from time tL to time t3 when it is detected that the weight W matches wl is the end of the current replenishment period (in; the latest discharge period (H) in the past [time tL,)] The motor (6) is driven in the driving state of time t2 of the discharge period ()1) during the period from time t8 to time t4 when it is detected that the weight iw matches w2. (6), and during the period N from time t4 to time to, the monitor (6) is driven in the driving state at time (l) of the discharge period (H).

Figure 5 shows the main body of the control device (8) that can execute the operations shown in Figure 4.
(9) is the load cell in the weighing device (1), 0I is the A/D converter, and Q9 is the CPU.

0 is a memory, and OnH is a D/A converter that converts the control signal output from the CPU (b) into analog and applies it to the motors (6) and (7). In addition, CPU (Iυ
The upper and lower limit set values WU#WL and the target flow iF are set externally, and the predetermined set value Wlg
W2 is determined by dividing the upper and lower limit set values wU9wLO into eight equal parts.

FIG. 6 shows a control routine for the first screw feeder (3) by the CPU α. In this routine, C
First, check whether PUθυ is in the supply period (1) (
a-1) l,, if the emission period (H), then A/
I) Read the latest weight w from converter (11) (a
-2), then the first screw feeder per unit time (
Determine the ejection amount in 3), compare it with the target flow rate F, and adjust the motor (
6) Change the control signal to (a-8), check whether the latest weight w read in [a-2] matches the set value W2 @ W (and the lower limit set value wL (a-4')
:l [a -5)] (a -6) L/, (a -
If no match is detected in any of steps 4,) to (a-6), the process returns to (a-1) via other routines.

(a-4': When a match is detected in J, the (a-8
] Store the control signal to the motor (6) instructed by (a-7)L, (a-5) or (
When a match is detected in 8-6), the respective control signals at that time are stored in memory θ at address B and CK store (a-8).
(a-9) Do. When it is determined in (a-1) that it is the replenishment period (I), it is checked (a-10) whether the latest weight W is less than or equal to the set value w1, and (a-10, J, W≦
If w1 is determined, it is in period J, so from address C of memory 0 success, the above [a −9) 'T! 1. Read out the received control signal. The output (a-11) is output from the motor (6) via the motor controller (5). (a-10
), if W > W + is determined, then the latest M
ItJ = Check whether w is less than the set value w2 (a
-12) If it is determined that W:≦w2 at t, , (a-12), the control signal stored in the above (a-8) is read from the address B of the memory < 琲. Shi゛C
Output (a) to motor (6) via motor control device (5)
-18) Do. When it is determined that W>w2 in (a-12), it is the period M, so the control signal stored in (,-7) is read from the address A of the memory (2) and the motor (a>motor control device (5) Output (a
-14) Do.

In this way, since the control signal to the motor (6) is switched according to the heavy ILw even during the replenishment period CI), the flow rate fluctuation during the replenishment period CI) is improved compared to the conventional art.

In the above embodiment, the discharge period (H) immediately before the replenishment period (I)
), the control signal stored in the memory 0g was read out as it was and used in the replenishment period (I), but this was based on each set value W+ obtained during the past multiple discharge periods (H) Ic.
, W2 are subjected to moving average processing and then read out and used in the replenishment period (I), further improvement in accuracy can be expected.

In the above embodiment, the set values w1 and w in the discharge period (H)
2 and lower limit set value W1. Although control signals were stored for eight points, it is sufficient to store control signals for a plurality of points, and the accuracy can be expected to improve as the number of points stored increases.

In the above embodiment (a-8), the weight per unit time ff
This was an instantaneous flow rate control in which the weight reduction of 1w was controlled to become the target flow rate each time, but this could be controlled so that the total discharge amount from the start of discharge approaches the integral value of the target flow rate. The same is true.

As explained above, according to the control method of the present invention, the control signal of the discharge device can be controlled so that the discharge capacity of the discharge device is almost constant according to the weight of the material to be discharged in the weighing hopper even during the replenishment period. Therefore, the accuracy of constant flow discharge is improved compared to the conventional method.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of the Constant Fino Dware, Figure 2
The figure is an explanatory diagram of the conventional control method, Figures 3 to 6 show a specific embodiment of the control method of the present invention, Figure 8 is a diagram of the relationship between raw material weight and discharge capacity, and Figure 4 1 is an explanatory diagram of storage and reading of control signals, FIG. 5 is a configuration diagram of the main body of the control device and its surroundings, and FIG. 6 is a flowchart diagram of the main part of FIG.
, (2)...Weighing hopper, (3)...
・・・・・・First screw feeder [discharge device],
(8)・・・・・・Control device main body, θυ・・・−
・・・CPU, (la...Me79, (H)・Curved surface discharge period, (I)・・・・Replenishment period agent Yoshihiro Morimoto feces greedy +- Toichi "轡-≧ 4 Chair-9-1 ≧ Figure 5,, rlZ Figure 6

Claims (1)

[Scope of Claims] 1. A control signal is sent to the discharge device so that the weight of the discharged material in the needle hopper reaches a lower limit setting value, so that the discharged material is discharged from the weighing hopper at a constant rate according to a decrease in the weight. In addition to controlling the bow, a plurality or more of the control signals are stored in correspondence with the weight level during this ejection period, and when the weight falls to the lower limit set value, a penalty is sent to the weighing hopper until the upper limit set value is reached. Continuing almost constant flow replenishment of the discharged material, and during this replenishment period, the past control inventory d, which has been memorized in advance, is maintained.
The constant feed number is read out sequentially according to the weight level of the discharged material in the weighing hopper and output to the discharge device. How to control doware. 2. The constant fee system according to claim 1, wherein the past control signal stored in advance is a moving average value of control signals for each weight level of a plurality of past discharge periods. How to control doware.