SU1761377A1 - Method of preparing molding and core compounds and device therefor - Google Patents

Abstract

Use: in the foundry industry in the preparation of molding and core mixtures in mixers with vertically rotating rollers to improve the quality of the prepared mixtures and reduce energy consumption, as well as improve the reliability of the installation for the preparation of the mixture. SUMMARY OF THE INVENTION: The method includes dispensing the starting components, mixing them in a mixer with vertical rollers, continuously determining the compactibility according to the height of the mixture layer compacted by the rollers in the mixer, and introducing water depending on the difference between the set and determined compactibility of the mixture. The compactibility of the mixture is determined by the formula Y A + BH - Cm, where Y is the compactibility of the mixture,%; H - the height of the layer of the mixture, compacted roller mixer, mm; m is the mass of the batch, kg; A, B, C - constant coefficients. The implementation of the method is carried out in a device comprising a mixer 1 with a vertical drive shaft 9, vertical rollers, meter 3 of the height of the mixture 2, regulator 4. The meter of height is designed as a cable; one end of the roller connected to the levers and located in the pipe, the upper part of which is mounted coaxially with the drive vertical shaft 9, the second end of the cable is fixed in a movable rod connected by coupling to the linear displacement transducer, the output of which is, like the outputs of the setters for compacting the mixture 5 and the total mass of the source components 6, connected to the inputs of the regulator 4. and its output is connected to the drive of the water supply pipeline valve. 2 sp of f-crystals, 3 ill., 1 tab. with with VI about with h VJ

Description

The invention relates to a foundry and can be used to prepare molding and core mixtures in mixers with vertically rotating rollers widely used in foundries.

There is a method of preparing a molding mixture, which includes dosing

starting components, mixing them in a mixer, taking them out of the mixer and transporting them to the measuring device, measuring the compactibility of the prepared mixture according to the degree of introduction of the roller into the mixture layer previously compacted by other rollers, comparing the measured value of compactibility with the specified one and introducing water into the mixer until equality measured and specified value of compacted ™ mixture.

In this technical solution, the regulation of the water supply to the mixer is made according to the measurement results of the compacted ™ mixture obtained by the device outside the mixer and connected to the mixer by transport communications, which increases the energy consumption for the preparation of the mixture and reduces the quality of regulation due to additional measurement errors the compactibility of the mixture caused by the transport lag of the measurement operation will be flattened and the low representativeness of the controlled sample, usually than 1% by weight of the prepared mixture. Increasing the representativeness of the sample increases the return to the mixer unmixed mixture, reduces the performance of the mixer and increases the cost of preparing the mixture.

A known method of preparing molding and core mixtures, adopted as a prototype, includes dispensing initial components, mixing them in a mixer with vertical rollers, continuously controlling the height of the mixture layer and supplying water to the mixer when the measured height of the mixture layer is equal to a given level.

The known device for the preparation of molding and core mixtures, selected as the prototype of the claimed device, contains dispensers of initial components, a mixer with a driven vertical shaft, on which a traverse is fixed, provided with sleeves and pivotally-mounted levers, with hinged-mounted vertical rollers , a mixture height meter fixed on the mixer traverse, a regulator connected to the water pipeline valve.

The disadvantage of the known method and device is that the unstable surface of the loosened mixture is controlled, located between the end surface of the roller and the mixer shell, which leads to large fluctuations of the sensor of the mixture level, water consumption and compaction of the mixture. In addition, the means for measuring the height of the layer of the mixture used in the implementation of the method introduces additional errors in measuring the density of the mixture, i.e. they control a small part of the surface of the mixture located in the mixer (no more than 5%), and the sensor slip in the abrasive molding mixture leads to its wear, change in weight and shape due to sticking

mixture, which affects the amount of its immersion in the mixture and the measurement results, reduces the reliability of the installation. The use of a mixture level sensor creates additional resistance to the movement of the mixer crosshead and requires additional energy consumption. The known method does not allow regulating the process of preparing a mixture in case of a change in the mass of the mixture.

sand as It is designed for the constant mass of the mixture.

The aim of the invention is to improve the quality of the molding sand being prepared and to reduce energy consumption during

preparation of mixtures, as well as improving the reliability of the installation for the preparation of the mixture.

The goal is achieved by the fact that in the method of automatic control

compactibility of molding and core mixtures, including the dosing of initial components, their mixing in a mixer with vertical rollers, continuous determination of compactivity by the height of the mixture layer in the mixer and the introduction of water depending on the difference between the specified and measured values of the mixture compactibility, according to the invention, the height of the compacted layer is measured

mixtures, and the compressibility of the mixture is determined by the formula

Y A + BH-Cm,

where Y is the compactibility of the mixture,%;

H - the height of the layer of the mixture, compacted roller mixer, mm;

m is the total mass of the components of the mixture, kg;

A, B, C - constant coefficients.

This goal is also achieved by the fact that in an installation for the preparation of molding and core mixtures, including dispensers of initial components,

a mixer with a vertical drive shaft, on which a traverse is attached, equipped with plows and pivotally mounted levers with pivotally mounted vertical rollers, the gauge

the height of the mixture, mounted on the traverse of the mixer, the regulator connected to the valve of the water pipeline, according to the invention, the meter height of the mixture is made in the form of a cable, one end connected to

the roller lever and located in the pipe, the upper part of which is mounted coaxially with the vertical drive shaft, the second end of the cable is fixed in the movable silt located in the pipe, coaxially with the vertical shaft, and under the shaft

connected to the primary linear displacement transducer, the output of which, as well as the outputs of the sets of compacting the mixture and the total mass of the initial components, is connected to the input of the regulator, and its output is connected to the drive of the water pipeline valve.

The proposed method was tested at VNIIlitmash on the basis of a laboratory mixer with vertically rotating rollers with a nominal batch volume of 0.005 m3.

Tests were carried out on mixtures of the following composition:

quartz sand

marks 1К01А Lyubertsy karera89-94;

activated bentonite Bulgarian 6%;

water 1-5%;

mixing weight 4-5 kg.

Before the start of each experiment, the measurements were made: the distance between the bottom of the mixer and one of the rollers with an error of ± 0.1 mm: the bulk components of the mixture were weighed with an error of ± 3 g, the dose of water was measured with a measuring cylinder and with an error of ± 1 mm.

The tests were carried out in the following sequence.

Sand with bentonite was loaded into the working mixer, mixed for 1 min, and a dose of water was injected. The minimum distance from the bottom of the mixer to the cylindrical surface of the roller was measured with a gauge with the mixer stopped. The measurement of the distance between the bottom and the roller was repeated in each experiment 10 times with an interval of 1 minute with a total mixing time of 10 minutes. Three samples were taken from the prepared mixture, and their compactibility was determined on the modulus measuring device. 315-С1 of the company G. Dieter (USA).

According to the results of the experiments, the maximum height of the mixture layer compacted by the mixer roller and the average value of the mixture compaction were determined.

As a result of processing the data presented in the table, a generalized empirical relationship is obtained between the compactibility of the mixture (V), the height of the layer of the mixture (H), compacted by the mixer roller, and the kneading mass (t)

Y A + BH-Cm, where A, B, C are constant coefficients.

With a moisture content from 0 to 2.75% and a bentonite content of 6% using regression analysis, it has been established that the above relationship has the form

Y 7.67 + 6.096H - 10.609t

The control regression coefficient is 0.88.

The coefficient of the data in the table shows that the error of the method with a water content in the range of 2.5-2.75% with a mixture compactibility of 50–5% (in the range of actual requirements for molding mixtures in foundries) is from 6.4 to 14, 2%, average relative

The measurement error of compactibility in the specified range is equal to 9.4% and commensurate with the permissible error value equal to ± 10% according to paragraph 2 of GOST 23409.13- 78.

FIG. 1 shows the installation diagram

for the preparation of molding and core mixtures; figure 2 is a top view; Fig. 3 is a view along arrow A in Fig. 1, which shows a meter for the height of the compacted mixture in the section.

The installation for the preparation of molding and core mixtures contains a mixer 1 with a mixture to be compacted 2, a measuring instrument 3 of the height of the compacted mixture 2,

controller 4, setters for compressibility of mixture 5 and the total mass of components 6 and water metering device 7.

The mixer 1 is equipped with a bowl 8, a vertical shaft 9 connected to the drive

mixer (not shown), a crossbeam 1.0, mounted on a vertical shaft 9, equipped with plows 11, 12, levers 13, 14, pivotally connected to the crosshead 10 and vertical rollers 15, 16.

The height gauge of the compacted mixture 3 (see Fig. 3) includes a cable 17 laid in a tube 18, a rod 19, a coupling 20, a linear displacement transducer 21, cuffs 22, 23,24, guide pins

25. The pipe 18 is attached to the traverse 10 with clamps 26 and screws 27. The lower end of the cable 17 is inserted into the hole of the lever 13 and secured therein by a screw 28, and the upper end of the cable is fixed in the rod 19 by a screw 29. Upper

the vertical part of the pipe 18, the rod 19, the coupling 20 and the linear displacement transducer 21 are mounted coaxially with the vertical shaft 9. The pipe 18, the lever 13 and the rod 19, as well as the coupling 20 and the lid of the mixer 30 are connected by elastic cuffs 22, 23, 24 An inner ring of the radial bearing 33 is fastened to the upper end of the rod 19 with a screw 31 and a washer 32. The outer ring of which is mounted in the housing

couplings 20. to which the studs 25 fastens

a cover 34. A cover 34 by a screw 35 is connected to a plunger 36 of a linear displacement transducer 21. The transducer 21 is attached to the mixer lid 30 by a nut 37. The studs 25 are located in the holes of the mixer cover 30 and are closed by a cap 38. The output of the transducer 21. entering the meter the height of the compacted mixture 3 (Fig. 1) is connected to the regulator 4, the other two inputs of the regulator 4 are connected to the setpoint generator 5 and the setpoint generator of the total mass of the initial components 6. The fourth input of the regulator 4 is connected to the output of the water flow meter 39, water entering the dispenser 7. The output of the regulator 4 is connected with a drive 40 valve 41 mounted on the water pipe 42. In the controller 4 control law introduced the following:

Y A + BH-Cm

where Y is the compactibility of the mixture,%;

H - the height of the layer of the mixture 2, compacted roller mixer, mm;

m is the mass of the curtain, equal to the mass of the doses of the initial components and the dose of water that passed through the water metering device 7;

A, B, C - constant coefficients.

To clean the cylindrical surface of the rollers 15, 16 from excess molding sand 2, cleaning scrapers 43, 44 are used, fixed on the levers 13, 14. The gaps between the working edges of the plows 11, 12, the bottom and the shell of the mixer should not exceed 1-2 mm. The components of the mixture 2 are fed by dispensers 45.

In the initial state, when the mixer is unloaded, the rollers 15, 16, the levers 13, 14 occupy the lowest position determined by the position of the stops located on the yoke 10. The units 5, 6 enter into the controller the value of the required compactibility and the total mass of doses of the initial components (waste mixtures, sand, bentonite, etc.), the meter of the water flow meter 39 is brought to zero.

After the initial components are loaded into the working mixer 1. and then the rollers 15,16 are lifted from the stops, and the levers 13, 14 turn on the axles fixed in the traverse 10. The cable 17 moves in the pipe 18 (in Fig. 3 to the right), raises the rod 19, which, acting on the inner ring, the ball-bearing ring and the outer ring of the bearing 33, vertically moves the coupling housing 20, the guide pins 25, the cover 34, the plunger 36 of the primary linear displacement transducer 21.

moving in the holes of the mixer cover 30, prevent rotation of the coupling housing 20 and the plunger 36. The signal from the primary linear displacement transducer 21, proportional to the height of the mixture layer compacted by the mixer 1, is supplied to the controller 4, which is calculated by the actual seal ratio capacity of the mixture, prepared taking into account the mass of the replacement, which is defined as the sum of the initial components, determined by the settings of the metering devices, and the output signal of the water flow meter 7, is proportional to the dose of water entering the mixer with Beginning of the mixing cycle. The values of H and t are continuously fed to the controller 4, which calculates the compactibility value of the moldable mixture. When the calculated compaction value is equal to that entered by the compaction device 5, the controller 4 outputs a signal to the actuator 40 of the valve 41, which locks the pipeline 42 and stops the water supply to the mixer 1.

When the raw materials are mixed with water, the sand grains are covered with a clay-water shell, and the compactibility of the mixture increases from 5 to 50%. Due to the increased strength and reduced flowability of the mixture, most

It is guided under the rollers, the rise of which, as established by research, is closely connected with the sealing of the mixture.

The use of the invention provides the following advantages:

5 - due to the use of a massive mixer roller as a sensitive element when measuring the compactibility of the mixture, there is no need to use a specially made sensitive element, which increases the reliability of the installation,

this significantly increases the volume

mixture controlled for one revolution of the vertical shaft. The use of the roller is significant

reduces random fluctuations caused by the fall of individual pieces of the spent mixture under the sensitive element;

-the proposed technical solution does not require additional expenditure of energy consumed by the mixer drive for

0 overcoming resistance when moving in a mixture of a measuring device;

- when using the roller, wear of the sensing element is reduced, since sliding friction is replaced by rolling friction, which

5 increases the reliability of the installation;

- thanks to the cleaning scrapers, the constancy of the geometric dimensions and mass of the roller-body embedded in the mixture is ensured, which contributes to the stability of the results of measurements of the mixture compactibility

The use of the claimed invention is easily realized and will allow to obtain an economic effect as a result of an increase in the quality of the mixture.

Claims (2)

Claim 1. Method of preparing molding and core mixtures, including dispensing mixture components into a mixer with vertically installed rollers, mixing, determining the seal capacity of the mixture in the mixer and introducing water depending on the difference between the specified and measured values of mixture density, Owing to the fact that, in order to improve the quality of the prepared mixtures and reduce energy consumption, the height of the compacted layer of the mixture is measured, and the compressibility of the mixture is determined from the mathematical expression neither Y a + bH-cM, where Y is the compactibility of the mixture,%; H is the height of the mixture layer under the mixer roller, mm; M - the length of the mixture, kg; a, b, c are empirical coefficients. 2. Installation for the preparation of molding and core mixtures, containing metering components of the mixture with mass dose controllers, a mixer with a vertical drive shaft, a cross member, plows, vertically mounted rollers with hinged levers, a mixture layer height meter, a regulator with seal adjusters, connected to the water pipeline valve, characterized in that, in order to improve the quality of the prepared mixtures, reduce energy consumption and increase reliability, the height meter of the mixture layer is designed as a primary a linear displacement transducer with a coupling and a cable with a movable rod installed in a pipe, one end of the cable fixed to the roller lever and the other end connected to a movable rod mounted coaxially with the vertical shaft and connected by means of a coupling to the primary converter, the output and output of the sets masses of doses of the components of the mixture are connected to the input of the regulator. 2 GF Zj Ј1 U x hlf / L-dishi visa Hey