RU2578871C1 - Device for continuous extrusion of loose materials - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to continuous extrusion of solid articles from loose materials (chips, granules, powder etc). Device contains matrix and wheel with annular groove for material transportation. Increased force of pressing, compression strains in cross section material and production of solid articles with uniform density is ensured by the fact that the device comprises two working and one power rollers, as well as closed belt contacting with its internal surface with peripheral cylindrical surfaces of rollers, and outer surface with deformed material. Input working roller is installed rigidly on drive shaft and drive. Closed band is in contact with deformed metal along the arc equidistant cylindrical peripheral surface of the wheel.

EFFECT: spatial position of power roller is controlled by the degree of compression of elastic element, which provides the required force of band compression to deformed material.

4 cl, 11 dwg

Description

The invention relates to the field of engineering, in particular to the processing of metals by continuous extrusion, and can be used to obtain long billets from non-compact material, such as metal powder, shavings, granules, which allows to reduce metal loss during processing and to increase its physical and mechanical properties . This device also allows to obtain composite materials.

Known devices for pressing ("Device for continuous angular pressing", RF patent No. 2345861, IPC B21J 5/06, B21J 13/00, B21C 25/08, publ. 02/10/2009). The invention relates to a deformation processing of metals and can be used to obtain long-length ultrafine-grained metal billets with improved physical and mechanical properties. The device contains a driving impeller with a caliber, a block with an insert and an emphasis. These elements have working surfaces, the combination of which forms a pressing channel. The emphasis is installed on the platform, which moves by means of a stop screw for smooth adjustment of the height of the pressing channel. The disadvantages of this device is the low quality of the product, due to its heterogeneous density, as well as narrow technological capabilities.

A device for continuous extrusion (prototype) is also known (“Continuous Extrusion Device”, RF patent No. 2164832, IPC VC 23/00, VC 25/00, publ. 04/10/2001). The present invention relates to devices for the processing of metals by continuous extrusion, in which the feed material is introduced into the annular groove of the rotating wheel and then sent to the channel formed by the groove and the arcuate device. The disadvantages of the prototype are the low quality of the product, due to its heterogeneous structure and density, as well as narrow technological capabilities.

The technical effect that is achieved from the use of the invention is to improve the quality of the product by providing a uniform and higher density and expanding the technological capabilities of the device.

The specified technical effect is achieved by the fact that the device contains two working and one power rollers, as well as a closed tape, which connects the peripheral surfaces of the rollers with its inner surface, and contacts the deformable material with an external surface along an arc equidistant to the peripheral surface of the wheel. The working rollers are rigidly mounted on fixed axles spaced from the center of the wheel at a distance greater than the radius of the peripheral cylindrical surface of the wheel. The power roller is rigidly mounted on the movable axis, spaced from the center of the wheel at a greater distance than the centers of the working rollers, and is equipped with an elastic element to create pressure of the tape on the deformable material. The technical effect is also achieved by the fact that one of the power rollers is connected to the drive and ensures the movement of the tape at a speed exceeding the linear speed of the peripheral points of the wheel.

The essence of the invention is illustrated by drawings, where in FIG. 1 shows a cross section of a device for continuous extrusion of non-compact materials; in FIG. 2 is a cross section AA of the annular groove of FIG. one; in FIG. 3 is an enlarged image of a metal deformation zone I in FIG. one; in FIG. 4 - metal deformation along the cross section of the matrix channel; in FIG. 5 - the flow velocity of the deformable material along the cross section of the matrix channel; in FIG. 6 - the location of the cross-sections 1, 2 and 3 of the channel matrix; in FIG. 7 is a change in the flow velocity of the metal in cross section 1 in FIG. 6; in FIG. 8 is a change in metal flow velocity in cross section 2 in FIG. 6; in FIG. 9 is a change in the flow velocity of the metal in cross section 3 in FIG. 6; in FIG. 10 - distribution of hydrostatic pressure in the vicinity of the matrix and its channel; in FIG. 11 - change in the density of the material in the vicinity of the matrix and its channel.

The device for continuous extrusion contains an impeller 1 with an annular groove (Fig. 1), rigidly fixed to the drive shaft 2 (for example, using splines or dowels, not shown in Fig. 1). For feeding non-compact material (chips, granules, powder) into the annular groove, tube 3 is designed. The working rollers 4 and 5 are mounted respectively on the drive shaft 6 and axis 7, the centers of which are located at a distance exceeding the radius of the circumference of the periphery of the wheel 1.

The device also contains a power roller 8 mounted on an axis 9, preloaded by an elastic element, for example a coil spring 10. The shaft 6 and the axis 7 occupy a fixed position relative to the wheel 1, and the axis 9 can be displaced relative to the wheel when the spring 10 is compressed. The closed tape 11 is made of metal or other durable material in contact with its inner surface with the peripheral cylindrical surfaces of the rollers 4, 5, 8, the outer surface with the deformable metal 12 in an arc, an equidistant peripheral cylindrical surface STI wheels. Compression of the spring 10 provides a change in the spatial position of the power roller 8, and therefore, the required value of the force of pressing it against the deformable material.

The dimensions of the annular grooves of the wheel 1: B - width, h ₁ - height (Fig. 2, section aa). In the block 13 are the holder 14 of the matrix 15 and the stop 16 (Fig. 3). At the output of the matrix 15 in the channel 17 we get a compact (solid) product formed from non-compact (bulk) material.

A device for continuous extrusion of non-compact materials works as follows. Through the tube 3 non-compact material is fed into the annular groove of the impeller 1, rotating with an angular velocity ω. The impeller 1 and the metal tape 11 non-compact material is transported along an arc of a circle. The pressure regulation of the tape 11 on the deformable material 12 is carried out by compression of the coil spring 10 (other methods of pressure regulation are possible).

Due to the active friction forces between the contact surfaces of the non-compact material with the surfaces of the annular grooves of the wheel 1 and the belt 11, a hydrostatic pressure is created in the region of the stop 16, which is sufficient for continuous extrusion of the metal through the output channel 17 of the matrix 15. The linear velocity ν _{l of the} belt 11 is greater than the linear peripheral speed ν _{to the} wheel 1 (1-2)%, which contributes to compression and advancing the deformable material to the die 15. The combined effect of the rotary annular grooves and strips on the deformable material causes it to continuously extrusion through the outlet passage 17 of the matrix 15.

It was previously noted that the extrusion of the material using the prototype does not provide high quality products due to the different speeds of the material through the matrix. The difference in flow rates leads to an uneven density of the product and a decrease in other physical and mechanical characteristics.

To confirm this fact, the authors simulated the process of continuous channel-angle pressing of non-compact material (aluminum powder Din-AL-99.5 (550950F (300-500C)) in the Deform 3D software package with a wheel angular velocity of 1 ω = 1,046 rad / s , the drawing ratio (λ = 2.0-2.5), the diameter of the output channel of the matrix is 6 mm and the coefficient of friction of the deformable material with the material of the working elements of the device (µ = 0.1 and 0.7).

In FIG. 4, zone 1 is visible with pronounced metal deformation and an elongated structural network; zone 2 - with less pronounced deformation; zone 3 - with intense deformation formed on the walls of the channel of the matrix. The metal fibers adjacent to the walls of the matrix channel undergo intense shear deformations, as a result of which hard zones of the deformed material are formed.

As a result of the simulation, it was found that the difference in the flow velocities of its various layers, the angle α (Figs. 1 and 3) between the direction of movement of the metal in the annular groove of the wheel in front of the matrix and dominates the process of formation of the structure, metal density and pressure distribution in the deformation zone in the matrix channel, as well as the coefficient of friction µ of the deformable metal with the material of the wheel and matrix.

When using the prototype device under the action of active friction forces between the deformable material and the impeller, the metal layers adjacent to the surfaces of the annular groove have a higher flow rate than the layers that are affected by the reactive friction forces created by the fixed tooling elements. In the process of continuous extrusion of aluminum material through the matrix channel, a spread in flow rates from 3.11 to 225.0 millimeters per second was observed (Fig. 5).

Such a significant velocity gradient along the boundaries of the deformation zone leads to a dispersion of physical and mechanical properties and a decrease in the quality of the press product (to uneven density, etc.). To increase the density and its uniform distribution over the volume of the press product, it is necessary to increase the active friction forces, which increase the compressive forces and stresses in the deformable material located in the annular groove of the wheel and in the channel of the matrix itself.

Under the action of the friction force from the side of the wheel, the metal movement accelerates, when the stop 16 is reached, the metal brakes, forming the so-called hard zones (zones with minimum speeds). Hard zones, in turn, inhibit the central layers of metal moving at a higher speed.

In cross section 1 (Fig. 6), the metal speed is maximum in the vicinity adjacent to the wheel (Fig. 7); in cross sections 2 and 3, the speed is maximum in the center (Figs. 8 and 9).

When the angle of inclination α = 120 ° and 150 °, the hydrostatic pressure is less than when the angle α = 90 ° (Fig. 10). The pressure difference is from 80 to 200 MPa, that is 12-30%. Modeling found that the value of hydrostatic pressure of -352 MPa is insufficient for a high-quality process of consolidation of powder material.

Hydrostatic pressure decreases with a decrease in the friction force and an increase in the angle of inclination of the matrix. The use of extrusion materials with a friction coefficient µ = 0.1 is not recommended due to a significant deterioration in the process of powder consolidation due to insufficient hydrostatic pressure. A satisfactory flow of the powder consolidation process is observed at a friction coefficient of µ≥0.35.

The proposed device has two sources of advancement of the deformable material through the matrix, one of which is realized by rotation of the impeller 1, and the second by the movement of the closed tape 11, which allows increasing the active friction forces and providing compression stresses along the entire channel of the matrix.

Modeling the process of channel-angle pressing of non-compact material showed that when using the proposed device, the density of the deformable material becomes equal to unity already at the entrance to the zone of full contact with the working surfaces of the matrix, which makes it possible to obtain a compact material of the product with constant density at the exit from the channel (Fig. 11 )

Thus, the use of the proposed device for continuous extrusion in comparison with the prototype extends the technological capabilities of the device (allows you to get products from solid bar stocks, and from non-compact, i.e. granular material) and provides a yield of material with a more uniform density.

We establish analytical dependencies, on the basis of which we can explain the fact of improving the quality of the press product during operation of the proposed device.

The active friction force in the prototype is created due to the adhesion of the metal with the annular groove of the wheel and is determined by the formula:

$$F_{tR.\mathrm{but}P}=\left(B{R}_{\mathrm{one}}+2h_{\mathrm{one}}\left(R_{\mathrm{one}}+0.5h_{\mathrm{one}}\right)\right){\epsilon }_{\mathrm{one}}{\sigma }_{m\mathrm{one}}{\mu }_{\mathrm{one}}\text{(one)}$$

where B is the width of the annular groove;

R ₁ is the radius of the arc of a circle along which the bottom of the annular groove is outlined (Fig. 2);

h ₁ - the height of the annular groove;

ε ₁ - the Central angle of contact of the pressed material with the wheel (Fig. 1);

σm ₁ is the pressure of the deformable metal on the walls of the annular groove;

µ ₁ - coefficient of friction of the deformable material on the material of the annular grooves of the wheel.

The friction force of braking (drag force) arising from the operation of the prototype,

where ε ₂ is the central angle corresponding to the arc of contact of the deformable material with the elements of fixed equipment;

F _{Tr m} - the friction force of the deformed metal during its passage relative to the stationary matrix.

The pressing force of the material during the work of the prototype

Active friction during operation of the proposed device

µ ₂ - coefficient of friction of the deformable material on the material of the tape 11 (Fig. 1).

The friction force of braking that occurs when the proposed device

The pressing force of the material during operation of the proposed device

A comparison of expressions (3) and (6) shows that the pressing force when using the proposed device is higher than that of the prototype, which positively affects the compaction of the deformable material, and therefore, the alignment of the density of the press product in volume. The fact that the density is equalized over the volume of the mold is confirmed by FIG. eleven.

Due to the fact that the linear speed of the tape is slightly higher than the speed of the drive wheel, there is an additional compression force of the deformable material around the periphery, which also contributes to its compaction. The creation of large compressive stresses in the cross section of the deformable material by using the proposed device allows to obtain solid products from non-compact material and to provide a more uniform density of the finished product, that is, to ensure its higher quality.

Claims (4)

1. Device for the continuous extrusion of non-compact materials, containing a matrix and a wheel with an annular groove designed to transport material to the matrix, characterized in that it contains two working rollers, one power roller and a closed tape that connects the peripheral cylindrical surfaces of the rollers with its inner surface and the outer surface is in contact with the transported material along an arc equidistant to the peripheral surface of the wheel. 2. The device according to p. 1, characterized in that the working rollers are rigidly mounted on fixed shafts located at a distance from the center of the wheel exceeding the radius of the peripheral cylindrical surface of the wheel. 3. The device according to p. 1, characterized in that the power roller is rigidly mounted on a movable axis located at a greater distance from the center of the wheel than the shafts of the working rollers, and is equipped with an elastic element to create pressure of the tape on the deformable material. 4. The device according to p. 1, characterized in that the power roller is connected to the drive to ensure the movement of the tape at a speed exceeding the linear speed of the peripheral points of the wheel.

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