RU2763131C1 - Bimetallic wire production method - Google Patents

Abstract

FIELD: wire production.SUBSTANCE: invention relates to the processing of metals by pressure and can be used for the manufacture of bimetallic wire. The method for bimetallic wire production includes the formation of a blank by wrapping around a cylindrical core made of steel 10 with a shell thread applied to its surface in the form of a flat strip of copper M1 and drawing. At the same time, before drawing, rolling is carried out in a roundup open groove with absolute compression equal to the height of the core thread h, while on the contact surfaces, trapezoidal projections of shell and core metals are formed sequentially, and the ratio between the areas of the corresponding trapezoidal projections of the core and shell is carried out:, where k is the empirical coefficient, with k=1÷2; Sshellis the area of the protrusion on the shell, mm2; Scoreis the area of the protrusion on the core, mm2;σTshellis the temporary resistance to rupture of the shell metal, MPa; σTcoreis the temporary resistance to rupture of the core metal, MPa.EFFECT: obtaining a bimetallic billet with a screw connection of the shell and core by rolling to ensure a high quality metal connection, as a result of which an intermediate layer with a hybrid self-wedging structure is formed, providing high adhesion of the shell and core.1 cl, 2 dwg, 1 tbl

Description

The invention relates to the processing of metals by pressure and can be used for the manufacture of bimetallic wire.

There is a known method of manufacturing steel-copper wire (see RF patent No. 2122908), including feeding a steel core and a copper sheath in the form of a tape, assembling a workpiece by wrapping the sheath around the core, joining its edges, heating to a temperature of 750-800 ° C and rolling the resulting workpiece into detachable round caliber. In this case, immediately before rolling, the surface of the copper cladding is cooled to a temperature of 200-400 ° C at a rate exceeding the rate of heat transfer in the steel core. The casing is cooled with cold air or a water-air mixture, mainly in the area of the round gauge connector.

The disadvantages of this method are the impossibility of obtaining a high quality connection of materials included in the bimetallic wire, as well as its high labor intensity, energy consumption and complex reproducibility.

The closest analogue is a method for manufacturing a bimetallic wire (see Japanese patent No. 54-155111), according to which, wire drawing is performed from a workpiece consisting of a sleeve with an internal thread and a core screwed into the sleeve from another metal equipped with a corresponding external thread. The threads are carefully ground, degreased, oiled and dried. After drawing, a wire is obtained in which there is completely no boundary between the two metals.

The disadvantages of this method are the impossibility of obtaining a high quality connection of materials included in the bimetallic wire, high labor intensity, energy consumption and complex reproducibility.

This is explained by the fact that when forming a workpiece, it is required to cut threads, identical in size, both on the inner surface of the shell and on the outer surface of the core. This leads to additional costs and makes it almost impossible to obtain long workpieces due to thread jamming. The use of a workpiece of small length to obtain a wire (long product), especially with a decrease in its diameter, requires the use of high total reductions, which causes a high work hardening of the shell metal and requires additional intermediate heat treatments, which leads to a high cyclicity of the process.

In addition, the joint plastic deformation of dissimilar metals during drawing in monolithic piles of a workpiece into a bimetallic wire causes a different stress-strain state in the protrusions in the threaded connection zone. This leads to their destruction and can lead to a complete loss of adhesion between the core and the shell.

The problem solved by the invention is to obtain a high quality connection of the metals included in the bimetallic wire, to reduce the cost of its production and to ensure the cyclicity of the process by creating an intermediate layer with a hybrid self-wedging structure.

The technical result, providing a solution to the problem, consists in obtaining a bimetallic blank with a screw connection of the shell and the core by rolling in a detachable round caliber, as a result of which an intermediate layer with a hybrid self-wedging structure is formed, providing high adhesion of the shell and the core.

The problem is solved by the fact that in the known method for the production of bimetallic wire, including the formation of a workpiece by wrapping around a cylindrical core made of steel 10 with a shell applied to its surface in the form of a flat copper strip M1 and drawing, according to the invention, before drawing, rolling is carried out in a round open gauge with absolute compression equal to the thread height of the core h, while on the contact surfaces, successively located trapezoidal protrusions of the shell and core metals are formed, and the ratio between the areas of the corresponding trapezoidal protrusions of the core and the shell is fulfilled:

where k is an empirical coefficient, with k = 1-2;

_Obol S - area of the projection on the casing, mm ^2;

S _heart - the area of the protrusion on the core, mm ² ;

σ _{Vobol - ultimate tensile} strength of the shell metal, MPa;

σ _{Vsrd - ultimate tensile} strength of the core metal, MPa.

There is a known method for the production of bimetallic wire (see Japanese patent No. 54-155111), according to which the wire is drawn from a workpiece consisting of a sleeve with an internal thread and a core screwed into the sleeve from another metal, provided with an external thread, respectively. This ensures a high quality connection of the metals included in the bimetallic wire.

In the claimed method, these features, as well as in the known method, are intended to create favorable conditions that ensure high quality adhesion of the shell and core metals, and reduce production costs.

However, along with the above known technical properties, the claimed set of distinctive features indicated in the claims, consisting in a synergistic effect from the action of successively carried out processes: threading on the surface of a cylindrical core, convolution of a strip from a soft component and the formation of a threaded connection between the core and the shell when rolling in a detachable round gauge and obtaining a hybrid self-wedging structure, provides high strength of the connection of wire components, reducing the cost of its production, as well as the cyclicity of the process.

Based on the foregoing, it can be concluded that the claimed method for the production of bimetallic wire does not follow explicitly from the prior art and, therefore, meets the requirement of patentability "inventive step".

The essence of the proposed method is illustrated by drawings.

FIG. 1 shows a core with a thread cut into it, where 1 is a trapezoidal protrusion on the core, 2 is a core.

FIG. 2 shows a diagram of the formation of an intermediate layer between the shell and the core during rolling, where 3 is a shell made of soft material, 4 is a trapezoidal protrusion on the shell; 5 - intermediate layer, h - the height of the protrusions of the core and shell.

The essence of the proposed method for the production of bimetallic wire is as follows.

On the surface of the wire - core (2, Fig. 1), a helical trapezoidal profile (thread) of a given configuration (1, Fig. 1) is preliminarily applied by any known method.

The inner surface of the shell (3, Fig. 2) is cleaned by any known method to remove oxide contamination. Preference should be given to brushing. Then the core and the shell are fed into a rolling stand with a round groove, where protrusions are formed on the shell (4, Fig. 2). In this case, rolling is carried out in a round open gauge with an absolute reduction equal to the height of the thread of the core h. As a result, a workpiece is obtained with an intermediate layer (5, Fig. 2), consisting of a hybrid self-wedging structure, and then drawing is carried out in monolithic dies to the finished size.

With simultaneous rolling in a round gauge of the core with the thread and the shell applied to its surface under the action of external pressure from the side of the rolling rolls, the gaps between the projections are filled with the shell material and the harder projections of the core (1, Fig. 2) are introduced into the shell material (3, Fig. . 2). That is, three layers are formed in the workpiece: surface (shell material), intermediate (5, Fig. 2), consisting of sequentially located sections of the materials of the shell (3, Fig. 2) and core (2, Fig. 2) and inner ( core material). Drawing in monolithic die of such a workpiece occurs according to the trimetal scheme. This provides a high level of mechanical adhesion between the sheath metal and the core.

Rolling a billet with a coefficient k <1.0 does not provide the adhesion strength of the protrusions due to insufficient ductility of the shell metal.

Rolling a billet with a coefficient k> 2.0 does not provide the adhesion strength of the protrusions on the surface due to uneven deformation of the shell and core metals.

An example of a specific implementation.

To substantiate the advantages of the proposed method for the production of bimetallic wire, 5 experiments were carried out, of which: experiments No. 2-4 with the claimed modes, No. 1, 5 - with modes outside the claimed modes.

A cylindrical billet made of steel grade 10 with a diameter of 30 mm and a length of 300 mm with a cut external thread was taken as a core. M1 copper tape was used as a shell. The tests were carried out with five options for threading the core.

The test results are shown in the table.

Based on the foregoing, it can be concluded that in the inventive method for the production of bimetallic wire, conditions arise for creating a hybrid self-wedging structure at the core-sheath interface, providing high adhesion of the sheath and the core. Accordingly, the claimed solution can be applied in rolling production, and therefore meets the condition of "industrial applicability".

Claims (7)

A method for the production of bimetallic wire, including the formation of a workpiece by wrapping around a cylindrical core made of steel 10 with a shell applied to its surface in the form of a flat copper strip M1 and drawing, characterized in that before drawing, rolling is carried out in a circular open gauge with an absolute reduction equal to the height of the thread of the core h, while on the contact surfaces sequentially located trapezoidal protrusions of the shell and core metals are formed, and the ratio between the areas of the corresponding trapezoidal protrusions of the core and the shell is fulfilled:

where k is an empirical coefficient, with k = 1-2; _Obol S - area of the projection on the casing, mm ^2; S _heart - the area of the protrusion on the core, mm ² ; σ _{Vobol - ultimate tensile} strength of the shell metal, MPa; σ _{Vsrd - ultimate tensile} strength of the core metal, MPa.

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