JPS62184831A - Setter of molding conditions - Google Patents

Abstract

PURPOSE:To make the error between the rotational frequency of a screw and the delivery rate extremely small and consequently the dimensional errors of a molded product a little by a method wherein a take-off speed or the rotational frequency of the screw is calculated and set on the basis of a regression curve of secondary degree, the group of coefficients of which is specified in accordance with the name of resin. CONSTITUTION:The relation of the rotational frequency N (rpm) of a screw and delivery rat E (g/min) is expressed by mans of the formula: E=aN<2>+bN=c in which a, b and c represent constants, which depend upon resin to be used. Four combinations of the rotational frequency of a screw and delivery rate relative to molding resin are measured and inputted through a key board 2 to an arithmetic and control unit (CPU) 1, in which a regression curve of secondary degree is set. The CPU 1 calculates coefficients a, b and c for every resin on the basis of the measured values and the regression curve by a least squares method in order to obtain an extrusion property. The CPU 1 sends rotational frequency signals based on the obtained rotational frequency of a screw. The signals are converted by a D/A converter 5 into analog signals so as to be set as the rotational frequency commands of a screw of an extruder 6. As a result, because the relation between the delivery rate and the rotational frequency of a screw is approximated by the regression curve of secondary degree, the error between the actual delivery rate and the rotational frequency of a screw is extremely small.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a setting device for calculating and setting the amount of resin extruded or the take-up speed of a molded product (thin film such as a film) in an extrusion molding machine.

(Conventional technology) Generally, when manufacturing films using an extrusion molding machine.

Molten polyJethylene is sent to the mold by extrusion.

Films are produced by cooling the molten polyethylene extracted through a flat slit.

When molding thin films such as films using an extrusion molding machine with a screw configuration, set the film width, thickness, and film take-up speed (winding speed), calculate the required extrusion amount from these, and determine the required amount. The screw rotation speed is calculated and set based on the extrusion amount.

Conventionally, in this type of extrusion molding machine, the relationship between the extrusion amount and the screw rotation speed is approximated by a straight line to calculate and set the screw rotation speed corresponding to the required extrusion amount, or every rotation (for example, 10
The extrusion amount for each rotation is stored in a memory, and the above-mentioned required extrusion amount, that is, the screw rotation speed, is calculated and set based on the extrusion amount for each predetermined rotation.

(Problems to be Solved by the Invention) Generally speaking, the relationship between the screw rotation speed and the extrusion amount is such that when the screw rotation speed exceeds a predetermined rotation speed, the extrusion amount no longer increases in proportion to the screw rotation speed. That is, as the number of revolutions of the screw increases, the saturation characteristic does not occur and the increase in extrusion amount decreases. Therefore, if the screw rotation speed is controlled as in (■) above, that is, if the screw rotation speed is approximated linearly, the screw rotation and the actual extrusion amount will not match, so the film thickness will deviate from the set value (error There is a problem that

On the other hand, when the screw rotation speed is controlled as in (■) above, the extrusion amount for each predetermined rotation of the screw is memorized,
This is because the required extrusion amount is controlled.

There are problems with extremely poor accuracy and errors in film thickness, and because more actual measurements are required, the user cannot easily change the formula (program) for calculating the screw rotation speed.

(Means for Solving the Problem) The present invention is a setting device for calculating and setting the resin extrusion amount or molded product take-up speed of an extrusion molding machine, and the relationship between the screw rotation speed and the resin extrusion amount is The screw rotation speed and resin extrusion amount, which are actually measured at at least three points for each resin, are input, and the coefficient group of the quadratic regression equation is set for each resin based on the measured values. and a storage means for storing the coefficient and the specific gravity of the resin corresponding to the resin, and during extrusion molding, the calculation control means is provided with the name of the resin, the screw rotation speed, and the take-up speed. When either one is input, the coefficient group is specified according to the name of the resin, and the take-up speed or the screw rotation speed is calculated and set based on the quadratic regression formula. .

E== a ×N +bN+c - (1) However, E is the resin extrusion rate (,9/min), and N is the screw rotation speed ('P
m) * a + b # and C are coefficients.

(Example) The present invention will be explained below with reference to Examples.

Referring to FIG. 1, the molding condition setting device is an arithmetic control device (
(hereinafter simply referred to as CPU)1. and keys are 1 (input device) 2, CRT (output device) 3. Auxiliary storage device 4
．． and a D/A converter 5.

In general, the relationship between screw rotation speed and extrusion amount is as shown by the solid line in Figure 2. As the screw rotation speed increases, the extrusion amount no longer increases in proportion to the screw rotation speed (as the screw rotation speed increases, the extrusion amount stops increasing). increase in volume decreases). That is, the relationship is not a straight line as shown by the broken line. The relationship between the screw rotation speed (N (rpm)) and the extrusion rate (El/min) is expressed by a quadratic regression equation shown in equation (2).

E = a N + b N 10c - (2) However, +
asb+ and C are constants (
coefficient) Here, with reference to Figure 3, the screw rotation speed and extrusion amount are set to 4 depending on the molding resin (for each type of molding resin).
(It is necessary to actually measure at at least 3 points),
This actual measured value is input to the CPU 1 using the key 2 (step 101).

The quadratic regression equation shown in Equation (2) above is set in advance in CPU 1, and CPU 1 calculates coefficients for each resin based on the above measured values and Equation (2) using the least squares method. b, and. is calculated and used as extrusion characteristics (Step 1
02). That is, if the measured extrusion amount is E,' and the calculated value obtained from the measured screw rotation speed (N1) is El, then 2 of the difference between the measured value E and the calculated value E shown in equation (3) is
Calculate coefficients a, b, and C that minimize the sum of products (Q). In this case, equation (3) is used as a and b, respectively.

What is necessary is to solve the simultaneous equations that are differentiated by and C and set to zero (Equation (4)).

Extrusion characteristics (a, b) calculated in this way.

C) is stored in the auxiliary storage device 4 along with the specific gravity in correspondence with the name of the resin (step 103). At this time the CRT
3 displays input of actual measurement values and calculation results.

Referring to FIG. 4, when molding a film with the extrusion molding machine 6, the key is pressed from the -door 2 to the film width (W (m)) of the film.
), film thickness (1 (μm)), film take-up (winding) speed (v (ffIlo)), and resin name are input (
Step 201 ), CPU 1 is connected to auxiliary storage device 4
The specific gravity CP of the resin corresponding to the resin name from (1/cyn3
)) and recall the extrusion properties (a, b, and C) described above.

First, extrusion ff1(E([/min))
Calculate (Stenoa °202).

E= tXlo XWXIQ XvXlo X/l
) ・(5) Next, the extrusion amount determined by equation (5) @)
Using equation (6), the screw rotation speed (N
(rpm) ) is calculated (step 203).

a CPU 1 is the screw rotation speed N obtained in this way
Sends out a rotational speed signal based on This signal is converted into an analog signal by the D/A converter 5 and set as a screw rotation speed command for the extrusion molding machine 6.

In addition, screw rotation speed (sha), film width (a)
.

The film thickness (t) and resin name may be input, the take-up (winding) speed (b) may be determined, and the take-up speed (g) command may be set.

In this case, as shown in FIG. 5, the extrusion amount (2) is determined by equation (2), and the take-up speed (b) is determined by secondarily transforming equation (5).

Since the extrusion amount and the scree rotation speed are approximated by a quadratic regression equation in this way, the error between the actual extrusion amount and the scree rotation speed is extremely small, and therefore the film thickness can be controlled almost to the set value. I can do it.

(Effects of the Invention) As explained above, by using the molding condition setting device according to the present invention, it is possible to store a large number of coefficient groups (resin properties) and specific gravity, and the resin properties can be used in the form of a quadratic equation. Since the screw rotation speed and extrusion amount are determined, the error between the screw rotation speed and the extrusion amount is extremely small, and there is almost no dimensional error in the molded product.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a molding condition setting device according to the present invention, FIG. 2 is a diagram showing the relationship between extrusion amount and screw rotation speed, and FIG. 3 is a flowchart explaining the calculation of resin properties.
FIG. 4 is a flowchart for explaining the setting for calculating the screw rotation speed, and FIG. 5 is a flowchart for explaining the setting for calculating the take-up speed. 1... Arithmetic control unit, 2... Key is in - mode, 3...
CRT. 4... Auxiliary storage device, 5... D/A converter, 6...
・Extrusion molding machine. Figure 2 Screw rotation speed (rpm) Figure 3

Claims (1)

[Scope of Claims] 1. A setting device for calculating and setting the resin extrusion amount or molded product take-up speed of an extrusion molding machine, wherein the relationship between the screw rotation speed and the resin extrusion amount is expressed by equation (1). Arithmetic control that calculates the coefficient group of the quadratic regression equation for each resin based on the input of the screw rotation speed and resin extrusion amount set by the following regression equation and measured at least three points in advance for each resin. and a storage means for storing the coefficient group and the specific gravity of the resin corresponding to the resin, and during extrusion molding, the calculation control means is provided with the name of the resin, the screw rotation speed, and the take-up speed. is input, the molding condition setting device specifies the coefficient group according to the name of the resin, and calculates and sets the take-up speed or screw rotation speed based on the quadratic regression formula. . E=a×N^2+bN+c...(1) However,
E is the resin extrusion rate (g/min), N is the screw rotation speed (r
pm), a, b, and c are coefficients.