RU1787781C - Molding process control method - Google Patents

Abstract

The invention relates to the production of articles by extrusion and can be used in the building materials industry, where the extrusion of these products is used, for example, in the manufacture of ceramic tiles. Improves control accuracy. To achieve the set circuit, measure the humidity and pressure of the press, simulate the process of pressing on a laboratory press at pressures of 10 and 30 MPa, measure the thickness of the sample at and without pressures by the values of the thickness of the sample and the moisture of the press powder calculate its compaction coefficient, the value of elastic expansion and the reciprocal of the density, from which the optimal value of the compaction pressure is calculated, and the change in the compaction pressure is carried out by the deviation of the measured current value from the calculated optimal pressure value. 2 tablets, 1 ill. s / s

Description

FIELD OF THE INVENTION This invention relates to the manufacture of articles by extrusion and can be used in an intentional ™ construction; materials where these products are pressed, for example, in the manufacture of ceramic tiles.

The purpose of the invention is to improve control accuracy.

The quality of products (ceramic) is evaluated by a set of indicators, which can be conditionally divided into the following three groups:

indicators characterizing the stability of the geometric dimensions and shape of the products;

indicators characterizing the appearance and surface quality;

indicators characterizing the physicomechanical properties, and other specific exploitation properties of the products. . - -.

All three groups of quality indicators are strongly influenced by porosity (density of pressed tiles), which affects the passage of all drying, glazing and firing processes. Therefore, it is important to carry out the process of pressing the tiles, creating the optimum pressing pressure at which the required density of the pressed tiles is ensured for any molding properties of the press powder, which is carried out by this method.

VI

00 VI VI 00

In the method of controlling the pressing process, including measuring the moisture of the material and changing the pressing pressure, a sample of the press powder is taken, which is placed in the matrix of the laboratory press, a pressing pressure of 10 MPa is created on the punch and, after some time delay, the value of the thickness of the pressed sample is fixed under the influence of this pressure. After that, the pressure is removed and the value of the sample thickness is again fixed, the change of which is caused by the action of elastic deformation forces. Then a pressure of 30 MPa is created and the fixation of the sample thickness values is repeated after some exposure to pressure and after it has been removed.

The choice of pressure steps of 10 and 30 MPa is explained by the working zone of pressure change during two-stage pressing of ceramic tiles, bricks and other products (10 MPa is the first step; 30 MPa is the second step).

The inverse values of the average density of samples under pressure and after depressurization for each stage are calculated from the measured values of the sample thickness and humidity of the press powder by the formulas:.

1 / At he K -0.1 h

nude

 K-gmo: (1) 1 / Wonzo 0.1 K from:

1 / Wozo 0.1 K-Iso, (2)

where bn, hio is the sample thickness under a pressure of 10 MPa and after its removal, mm;

Lnzo, is the thickness of the sample under a pressure of 30 MPz and after its removal, mm;

K is a coefficient depending on the dimensions of the matrix of the laboratory press, as well as the mass and humidity of the sample powder press, determined by the formula; .., ..

TO

5m

,. W

y (i -TOO)

where 5m is the area of the laboratory matrix

press, cm2;

m is the mass of the sample of the press powder, g; W is the moisture content of the sample powder press,

%

The molding properties of the press powder are calculated using the following formulas

Soup (1 / Wanyu-1 / WonzoU1.009- (4) 1 / won 2,303-Soup + 1 / wonyu: (5) EP 0 / Woyu + 1 / Woozo 1 / Wonyu - 1 / Wonzo) / 2. (6)

where Soup is the compression ratio of the press powder, cm3 / g;

1 / Won The inverse of the density of the press powder under a unit pressure, cm3 / g;

Ep is the elastic expansion of the press powder, cm3 / g.

After calculating the values of the molding properties of the press powder, determine the pressing pressure for the laboratory press by the formula

R e

1 / Won + Er-gt5

USP

up

()

where Rl is the pressing pressure on the laboratory press, MPa;

Successful is the required density of freshly formed tiles, g / cm3 (determined experimentally at the enterprise for these firing and glazing modes, based on the required value of tile water absorption).

Working pressure

the press is determined by the formula

PP e In RL +

D.

Soup

(8)

Xq

dg

fifty

where Rp is the pressing pressure on the working press, MPa;

Dn is a dynamic correction equal to the difference between the inverse values of the density of samples pressed on a laboratory press under quasi-static pressing conditions and tiles pressed on a working press in dynamic mode at the same pressing pressure, cm / g (for ceramic tiles widely used in factories presses KRK-125 dynamic correction Dn is 0.0314 cm3 / g).

The oil pressure in the hydraulic system of the working press is calculated by the formula

(9)

where L is the ratio of the area of the pressing piston to the total area of the press dies (from the technical characteristics of the press).

The control of the process of changing the pressing pressure on the working press can be carried out automatically or manually. For this, the current value of the pressing pressure on the press is measured with a pressure sensor (manometer). Then, the calculated pressure value is compared with the measured value. If the calculated value is greater than the current value, then, using the regulatory body, increase the pressing pressure on the press to the calculated value. In a similar manner, the compression pressure is reduced if the calculated value is less than the current value of the pressing pressure.

 The drawing shows a diagram of an implementation of a method for controlling a pressing process.

The following notation is adopted in the drawing: hopper 1. in which there is a press powder, sleeve 2, work press 3, pressed tiles 4, conveyor 5. The work press is equipped with a pressure stabilization control system consisting of a pressure sensor 6, a regulating device 7, the regulator 8 and the setter 9. On the conveyor 10 for feeding the press powder into the hopper 1, there is a moisture meter 11 for measuring the moisture content of the press powder.

To measure the thickness of the pressed sample of the press powder, an indication device 12 is used, associated with the die 13 and the punch 14 of the laboratory press 15; the pressure generated by the latter is measured by a pressure gauge 16. The input of the computing device 17 is connected to a moisture meter 11, and the output to a summing device 18, the other input of which is connected to a pressure sensor 6, and the output to a control device 7.

Example (implementation of the method). Using a moisture meter 11, the moisture content of the press powder is measured on the conveyor 10, for example 4.3%, a sample is taken there, a press powder of a certain mass, for example. Example 20 ± 0.1 g, place it in a matrix 13 with an area of 30 cm2 of laboratory press 15. On the punch 14 of laboratory press 15, a first pressing pressure of 10 MPa is created. After 10-15 seconds, the thickness of the pressed sample is measured using an indicating device 12, for example, dash10 3.68 mm. The first pressure is then removed and the thickness of the pressed sample is again measured, for example, hio 3.81 mm. Then create

the compaction pressure was 30 MPa, and the fixation of the sample thicknesses under pressure (L0.35 mm) and after it was removed (From 3.42 mm) was repeated. Based on the measured values of the sample thickness and humidity of the press powder, the molding properties of the press powder are calculated according to formulas (1), (2), (3), (4). (5), (6) and from formula (7), the optimum value of the compaction pressure for the laboratory press is determined. Then, using the formulas (8) and (9), the optimal value of the pressing pressure and the pressure in the hydraulic system for the working press are determined, providing the optimal

5 tile density 1.78 g / cm.

The dynamic correction for the single-stamp press KRK-125 is 0.0314 cm / g, and the ratio of the area of the pressing piston to the area of the stamp L is 3.6.

0 Initial data and calculation results are given in table. 1 and 2.

As follows from the drawing, the change in the pressing pressure can be carried out automatically or manually. The compaction pressure is calculated using block 17 according to expressions (1) - (9). The unit is implemented on the basis of the UVKSM-1300 and has a digital display or a communication device with an object that has an output

0 signal 0-5 mA.

Manual change of the pressing force is carried out by means of the setter 9. In this case, the optimal value of the pressing pressure is set on the setter,

5 obtained on the UVK-SM-1300 display when calculating expressions (1) - (9). When manually changing the pressing pressure, the signal from the setter 9 is fed to the first input of the control device 7, to the second

To the input of which the output of pressure sensor 6 is connected. In the event that the signal from setter 9 is greater than the signal from sensor 6, the regulating device 7 generates a control signal in accordance with PN-5 law, which is transmitted to the regulatory body 8, which increases pressing pressure. Similarly, a reduction in compression pressure occurs. - Automatic process control

0 change in effort consists in the fact that the calculated optimum pressing pressure by block 17 is transmitted to the first input of the summing device 18 (signal 0-5 mA), to the second input of which

5, the signal from the pressure sensor 6, and the difference between the indicated signals is P - Pm - Ptek. where Rtek is the current value of the pressing pressure, is fed to the additional input of the control device 7, which in the same way as with manual control

in accordance with the PN control law, the compression pressure is changed.

The use of the method is most effective for controlling the pressing processes in the production of ceramic tiles.

Using the proposed control method allows obtaining tiles with a stable density.

Obtaining tiles with a stable density makes it possible to obtain higher quality fired tiles.

Claims (1)

The claims A method of controlling a pressing process comprising measuring moisture powder powder and changing the pressure, characterized in that, in order to increase the accuracy of control, measure the current value of the pressure and simulate the process of pressing on a laboratory press at pressures of 10 and 30 MPa, measure the thickness of the sample at these pressures and without According to the values of the sample thickness and humidity of the press powder, their compaction coefficient, elastic expansion value and inverse density value are calculated, from which the optimal value of the compaction pressure is calculated, and the pressure change Hovhan lead from the deviation of the measured current value from the computed optimum pressure value. Table 1 Initial data and calculation results indicators (harmonizing properties of the press powder Initial data and calculation results of pressing pressures in laboratory and working presses 1.76 0 3.6 16.8 table 2 . 28,2 7.83