JPS58128136A - Controlling method of granulator - Google Patents

Abstract

PURPOSE:To maintain pellet strength at target values at all times by operating the strength of the pellets from process variables such as the number of revolutions and load torque of a granuator and controlling the number of revolutions of the granulator in accordance with the results of the operations. CONSTITUTION:Powder 8 incorporated with thermoplastic binders is put in the hopper of a granulator 1, and first the relations between the strength (y) of the pellets granulated in a preliminary operation and an influencing factor xi are investigated and are formulated. For example, x1 is the number of revolutions Nr of rolls 4, x2; the load torque Tor of the rolls 4, x3; the number of revolutions Nf of a screw feeder 7, x4, the load torque Tof of the feeder 7, x<5>; the temp. T of the powder in the machine 1. When the equations are established, the operated value (y) coinciding approximately with the actually measured values is determined by measuring x1-x5. In order to maintain the value (y) at a target value y0 at all times, the x1 is fixed and the x3 is adjusted with an operator 20 for the number of revolutions via a controller 12 for the number of revolutions or the x3 is fixed and the 1 is adjusted with a controller 11 for the the number of revolutions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling a granulator that compresses powder into pellets, and in particular, in order to prevent breakage of the formed pellets, the strength of the pellets is improved. This invention relates to (2) a method for controlling a granulator suitable for maintaining the same value.

A conventional control method for a pre-kerating machine type granulator will be explained with reference to FIG. The granulator 1 includes a pair of rolls 4 that are rotated by a motor 2 and a transmission 3, and a screw feeder 7 that forces the powder 7 into the gap between the rolls 4 by the motor 5 and transmission 6. ing. Pockets 9 are provided on the surface of the roll 4, and when the roll 4 and screw feeder 7 are rotated, the powder 8 is compression-molded into pellets IO. At this time, in order to prevent damage to the granulated pellets that are the product, it is required to maintain the strength y (for example, crushing strength) of the pellets to a predetermined iIK. For this reason, the conventional company first calculates the roll rotation speed N and feeder rotation speed N1 to set the pellet strength y to the target value in a preliminary operation, and then sets them to the set value (N,
)-, (NtL), and a control method was used to maintain the pellet strength y at a predetermined value.

However, Peretz) 100 strength strength, number of rotations N,.

In addition to Nr, it also depends on process variables that change over time, such as the load torque of the granulator I, or the temperature of the powder during compression molding when granulating the powder by adding a thermoplastic binder. It is not easy to conduct an online non-destructive inspection of the strength y of the roll and screw feeders at their respective set values (Nt), , (Nt
) - Conventional fixed value control has the disadvantage that the strength of the pellet IO may decrease and pellet breakage may occur.

An object of the present invention is to provide a control method that can constantly maintain the strength of the product pellets at a target value when compression molding powder is granulated into pellets.

The present invention was devised based on the fact that the strength of granulated pellets [y] is influenced by various factors such as the rotational speed of the roll and screw feeder of the granulator, load torque, and the temperature of the powder during granulation. This is what I did. The characteristic line of the present invention is to formulate the relationship between the granulated pellet t) strength y and various influence factors, and use the nine formulas to change the number of revolutions of the screw feeder or roll, thereby increasing the pellet strength & y. An example of embroidery according to the present invention will be explained using Fig. 2, where the target value y is less than 1.

The small collar of the granulator 1 contains powder 8 mixed with a thermoplastic binder. First, the relationship between the strength y of the pellets granulated in the preliminary operation and the influencing factor Xi will be investigated and formulated. Here, 1, for example, X is the rotational speed Nt of the roll 4,
! , is the load torque T* of roll 4? When using the load regression analysis method where %"l is the rotation aN* of the screw feeder 7 and X4 is the screw feeder, the following is obtained.

)'=bo+b+Xt+b*x*tenbsXs+baXa
+bi"s ------・----(1) Here, %9 is the estimated value of pellet strength, b・, bl...s b4 is a constant determined by multiple regression analysis).

In the C multiple regression analysis, constants b·ebee...b are determined so that the square of the difference between the estimated pellet strength 111y and the actual value y measured during preliminary operation is minimized. ) Therefore, if formula (1) is found, % ”19
・If x4 is set to the needle side, an estimate 1y that is almost the same as the actual value -1ay can be obtained.

Next, using the formula (rl), the pellet strength is constantly set to the target value F
The control method to maintain the condition a is described below. Here, the roll rotation number N
-(=:x,) is fixed and the screw feeder rotation speed N*(=Xs) is adjusted. α) If we set Y”Y* in 2, it becomes. In Fig. 2,
20 is a means for calculating the rotation speed, and the target value)'(1s
Process amount x 1 (=N t ) of granulator l, x,
(=T,, ),X4 (=T-t)%)Im
With (=T) as input, calculate the formula
There is a function to output (= (Nt) -). Therefore, according to this embodiment, the strength of the granulated pellets [y] is always the target value y.

can be kept.

Other examples include the following. First of all, Verret's strength is 1111! In order to increase the accuracy of control to match fly, it is possible to use a high-order polynomial of quadratic or higher order instead of a linear equation such as the α) equation, or to use a compression molding physical model equation. . Second, fix %Nt and adjust the screw feeder rotational speed Ng by adjusting the %roll rotational speed Nt.
It is to adjust. Thirdly, as shown in #I2 diagram, Nt
without automatically changing the value, calculate the estimated value y of the pellet strength using equation (1), and display the result on a display device,
The operator is to adjust the rotary crocodile settings (NI) and tahiro (N) so that the estimated value y and the target value y6 match.

According to the present invention, the strength of pellets obtained by granulating powder can be maintained at a predetermined value. As a result, damage to the pellets can be prevented. Furthermore, since the pellet strength is not increased more than necessary, the electric energy required for operating the granulator can be saved.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a conventional method, and FIG. 2 is a diagram for explaining an embodiment of the present invention. l...Made 1ull, 4...Roll, 7...Screw feeder, Death...Powder, 10...Compression molded product, 11.12...Rotation number clause @* 20... Rotation speed calculator.

Claims (1)

[Claims] 1. In a pre-kerating machine type granulator that compresses and molds powder by rotating a screw feeder and forcibly pushing the powder into the gap between a pair of rotating rolls, A method for controlling a granulator, comprising means for calculating the strength of a compression molded product from process variables such as rotation speed and load torque, and means for changing the rotation speed of the granulator based on the calculation results. 2. In claim 1, means for calculating the rotation speed of the granulator to make the strength of the compression molded product match the target value;
and a method for controlling a granulator, comprising means for changing the rotation speed of the granulator based on the calculation result.