RU2352417C2 - Pressing method of profiles and matrix for implementation of current method - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: cylindrical work, heated till the deformation temperature, is fed to container and pressed out trough the matrix. Matrix allows working taper cavity and cell with calibrating section. While pressing out through the taper cavity of matrix blank metal is additionally subject to radial-shearing deformation. For this it is implemented at least one cycle, which includes declination of pressing axis in taper cavity per angle and its recovery. Angle value is 5-30°. Taper cavity of matrix contains at least one section consisting of two tandem taper surfaces. Centroidal axis of these surfaces are located in the same plane and declined in opposite directions relative to matrix axis.

EFFECT: improvement of received profiles.

4 cl, 3 dwg

Description

The invention relates to the field of metal forming and can be used in the manufacture of profiles, mainly rods, by hot pressing from difficult to deform materials, in particular from titanium alloys, and to the construction of a pressing tool.

The quality of profiles of hard-deformed alloys largely depends on the degree of deformation and the uniformity of its distribution over the volume of the workpiece.

A known method of plastic structuring of high-strength materials, including repeated extrusion and sediment of the workpiece with preservation of its original shape and size after each cycle of deformation, with each subsequent cycle of deformation, first extrude part of the preform through the working belt of the matrix, stop extruding, precipitate the extruded part of the preform, then, alternately extruding part of the preform and its upset is repeated until the entire preform is deformed, at m length embossed portion bounded 2.5 diameters running web matrix (RU 2116155, B21J 5/00, 27.07.98 g). This method provides the ability to form a given uniform metal structure throughout the body of the workpiece. The shape and size of the workpiece does not change.

This method is applicable only to products with limited geometric dimensions, is inefficient and requires additional technological operations to change the geometric shape of the products.

There is a method of producing metal rods by extruding a billet through a matrix containing a lead-in, a forming part with spiral grooves and a calibrating girdle, while on the lead-in part of the matrix there are made spiral grooves with an inclination to its forming surface opposite to the inclination of the grooves of the forming part of the matrix, while the ends of the grooves the lead-in part is offset relative to the beginning of the grooves of the forming part (USSR author's certificate No. 776692, class B21C 25/02, 1980) - prototype.

Pressing through such a matrix provides a sufficiently high level of shear deformations, the outer zones of the product being the most deformable, the deformation to the central part of the bar decreases, where an insufficiently deformed region is formed in which casting defects of the workpiece are preserved. It should be noted that the selection of the geometric shape and the number of grooves can intensify the deformation of the outer layers of the pressed product in the tangential direction, but have little effect on the movement of metal in its central part, which leads to anisotropy of the strip properties in the cross section.

The objective of the invention is the creation on standard equipment of a high-performance method for pressing metal profiles, which ensures that they receive a uniform fine-crystalline structure throughout the volume of the product, with the specified physical and mechanical properties.

The technical result achieved by the implementation of the invention is to improve the quality of extruded profiles by ensuring uniform deformation of the metal over the cross section of the extruded product, including its central part.

The specified technical result is achieved by the fact that in the method of pressing rods, comprising feeding a cylindrical billet heated to a strain temperature into the container, and extruding the heated metal through the working cavity of the matrix containing the working conical cavity and a point with a calibrating section, when extruding metal, on the working section conical cavity, is additionally subjected to radial-shear deformation by means of at least one cycle, including deviations of the pressing axis in the working cavity of the matrix tsy at an angle equal to 5-30 °, and its return to its original position.

,To intensify the process of developing the metal structure, radial-shear deformation is carried out by a series of successive cycles of deviation of the pressing axis in the working cavity of the matrix in several directions, rotated relative to each other by an angle φ equal to

,

where n is the number of cycles of radial shear deformation.

To accomplish this task, a pressing matrix is proposed that includes a working conical cavity of the matrix and a point with a calibrating section, characterized in that the working conical cavity contains at least one section of radial-shear deformation, consisting of two conical surfaces located in series, central axes which are located in the same plane and rejected in opposite directions relative to the axis of the matrix.

,For a deeper study of the metal structure, the working conical cavity may contain a number of sections consisting of two consecutive conical surfaces and rotated relative to each other by an angle φ equal to

,

where n is the number of plots.

Figure 1 presents a sketch of the matrix (side section), where

1 - working conical cavity;

2 - the first conical surface of the radial-shear strain section;

3 - the second conical surface of the radial-shear strain section;

4 - matrix point;

5 - output section.

Figure 2 - microstructure of a sample of a rod from a titanium alloy Gr2 made in a known manner.

Figure 3 - microstructure of a sample of a rod of titanium alloy Gr2, manufactured by the proposed method.

The profile pressing matrix comprises a working conical cavity 1, at least one section of radial-shear deformation, consisting of a first conical surface 2 and a second conical surface 3, the central axes of which are located in the same plane and are angled in opposite directions relative to the axis of pressing equal to 5-30 °.

Such a constructive solution allows introducing additional shear deformations during the pressing process due to the shear displacement of the workpiece material in the deforming working conical section of the matrix. An angle of deviation of less than 5 ° does not provide a uniform study of the central and peripheral layers of the workpiece, which leads to anisotropy of the strip properties in the cross section. An increase in the angle of inclination of the conical surfaces of the radial-shear strain section of more than 30 ° will lead to a cut of the outer layers of the workpiece and, accordingly, to the formation of stagnant zones filled with the workpiece material. The level of shear deformations in this case will be determined not by the matrix profile, but by the profile of the stagnant zones, as a result of which they are localized on the surface layers of the material being deformed, leading to anisotropy of the mechanical properties.

Implementation example

The pressing process is carried out with the lubrication of the press container, the deforming cone and the working belt of the matrix. The resulting workpiece, heated to a predetermined temperature, is placed in the press container, under the influence of pressure applied to the press stamp, the workpiece material fills the working conical cavity 1 and the section of radial-shear deformation, consisting of conical surfaces 2 and 3, while shear deformation in the entire volume of the workpiece. This is ensured by changing the direction of movement of the metal in the conical surfaces of the section of radial-shear deformation, as well as the minimum friction forces at the initial moment due to the introduction of lubricant. At the next stage, the workpiece material is extruded through a matrix point 4 in the form of a profile of predetermined dimensions. The further pressing process takes place in a stationary mode.

When using several radial-shear deformations, an additional shear and alignment of the flow rates of both the external and internal layers of the workpiece occur, which provides a significant comprehensive and uniform study of the workpiece and, as a result, high quality of the product in the heat-treated state.

To evaluate the comparative results, experiments were carried out on pressing bars with a diameter of 133 mm from Gr2 alloy using the proposed and known dies.

The deviation angle of the conical surfaces of the radial-shear strain section was about 18 °.

Pressing was carried out on a horizontal hydraulic press with a force of 3150 tf with a container diameter D _k = 280 mm and a workpiece diameter D _z = 275 mm. The temperature of the workpieces before deformation T _s = 830 ° C, the container T _to = 400 ° C. Thus, according to two technological schemes, the rods were pressed, from which the samples were made.

Figure 2 shows the untreated structure located in the central part of the bar (known method), where, in contrast to the structure in figure 3 (the proposed method), a highly homogeneous fine-grained macrostructure is formed over the entire cross section of the bar.

Thus, the present invention allows to obtain extruded rods from hardly deformable alloys with improved mechanical properties and low anisotropy of properties over the entire cross section of the profile. The process does not require design changes to traditional equipment.

Claims (4)

1. A method of extruding profiles, comprising feeding into a container a cylindrical metal billet heated to a deformation temperature, and extruding the heated metal of the billet through a die having a working conical cavity and a point with a calibrating section, characterized in that when the extruded metal is extruded through the working conical cavity of the matrix additionally subjected to radial-shear deformation by performing at least one cycle, including the deviation of the pressing axis in the working conical cavity of the mat ritsa at an angle equal to 5-30 °, and its return to its original position. 2. The method according to claim 1, characterized in that the radial-shear deformation is performed by a series of successive cycles with a deviation of the pressing axis in the working conical cavity of the matrix in several directions, rotated by an angle

,
where n is the amount of direction of radial shear strain. 3. A matrix for pressing profiles, containing a working conical cavity and a point with a calibrating section, characterized in that the working conical cavity contains at least one section consisting of two conical surfaces located in parallel, the central axes of which are located in the same plane and are deflected in opposite directions relative to the axis of the matrix. 4. The matrix according to claim 3, characterized in that the working conical cavity contains a number of sections consisting of two conically arranged conical surfaces and rotated relative to each other by an angle

,
where n is the number of plots.

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