RU2319559C1 - Wire production method - Google Patents

Abstract

FIELD: plastic working of metals, possibly manufacture of wire.

SUBSTANCE: method comprises steps of cold rolling of initial blank successively in driven, non-driven and then again in driven rolls with smooth barrel for producing intermediate square cross section of wire; performing rolling of blank in each pass at unit deformation degree determined depending upon respective diameter of roll at condition

where ε -deformation degree; d-size of cross section of blank, mm; D -roll diameter, mm. Then rolled wire is subjected to drawing in several passes through monolithic drawing dies till total deformation degree 85 - 95%. Drawing process is realized at unit deformation degree determined according to condition ε≥ 1 - ((1 -arctg ( tgα+ f))/(1 + arctg( tgα + f))² where α - angle half of drawing die, rad; ε - deformation degree; f - friction coefficient in deformation region.

EFFECT: improved plastic and strength properties of produced wire.

3 dwg, 1 tbl, 1 ex

Description

The invention relates to the processing of metals by pressure and can be used in the manufacture of wire from various metals and alloys.

A known method of manufacturing a low-carbon reinforcing wire, comprising rolling the initial billet in two passes in a twin roll gauge system, the deformation being carried out on smooth rolls with a deformation degree of 28-32% in the first pass to obtain an intermediate plane oval cross-section of the wire, and in the second pass the wire is deformed in a round caliber with a degree of deformation of 30-35% along its larger axis (see RF patent No. 2221654, B21B 1/18).

The disadvantage of this method is the manufacture of wire with low strength and plastic properties. This occurs as a result of the fact that rolling under these conditions does not provide uniform deformation along the cross section of the wire and, therefore, does not allow to obtain high plastic properties, and small total deformations are the cause of low strength properties of the wire.

где d - диаметр готовой проволоки (см. авт. св. СССР №1424900, В21С 1/00).The closest analogue to the claimed method is a method of manufacturing a wire, including cold rolling the original billet and the subsequent drawing of the wire in monolithic dies. In this case, rolling is carried out in multi-roll calibers, and drawing is carried out with a total degree of deformation within the following limits:

where d is the diameter of the finished wire (see ed. St. USSR No. 1424900, B21C 1/00).

The disadvantage of this method is the low strength and plastic properties of the manufactured wire. The low plastic properties of the wire are due to the appearance of large tensile longitudinal and circumferential stresses in its peripheral layers caused by uneven deformation along the wire cross section, and the low total degree of deformation is the reason for the low strength properties.

The technical problem solved by the invention is to increase the plastic and strength properties of the manufactured wire by creating uniform deformation along its cross section along the entire manufacturing route, ensuring the use of high total degrees of deformation.

The problem is solved in that in the known method of manufacturing the wire, including cold rolling the initial billet and subsequent drawing of the wire in monolithic dies, according to the invention, the cold rolling of the initial billet is carried out sequentially in drive, non-drive and then again in drive rolls with a smooth barrel with a single degree of deformation determined from the condition:

where ε is the unit degree of deformation;

d is the size of the section of the workpiece, mm;

D is the diameter of the roll, mm,

to obtain an intermediate square section of the wire, and wire drawing is carried out to a total degree of deformation of 85-95% with a single degree of deformation, determined from the condition:

where ε is the unit degree of deformation;

α is the half-angle of the die, rad;

f is the coefficient of friction in the deformation zone.

The consistent implementation of hot rolling in drive, non-drive and then again in drive rolls is known to simplify the drive circuit of the mill and reduce operating costs (see Japanese application No. 60-166103, B21B 1/16).

In the claimed method, this feature is also intended to simplify the drive circuit of the mill and reduce operating costs.

However, along with the known technical property, the claimed distinguishing feature during cold rolling allows you to create a new technical result, which consists in creating compressive stresses in the workpiece due to the significant pushing forces acting on the workpiece from the drive stand. This allows you to increase the plastic and strength properties of the manufactured wire at the stage of cold rolling.

Known is the operation of cold rolling a sheet or tape on a smooth barrel for metal shaping (see Rolling production. A textbook for high schools. Polukhin P.I. et al. M.: Metallurgy, 1982. - p. 483).

In the inventive method, the specified technique is also intended for metal forming. However, along with the well-known technical property of the claimed feature, characterizing cold rolling in series in drive and non-drive rolls with a smooth barrel and with the claimed deformation mode, it is possible to create a new technical property, which consists in creating the initial deformation penetrating the entire cross section. This provides a redistribution of slip systems and lines over the entire cross section of the workpiece, which are involved as a result of a change in the deformation scheme during the transition from the first pass to the second, from the second to the third, as well as during the transition from rolling to drawing. Thus, the activation of the free slip planes creates favorable conditions for subsequent deformation, which leads to an increase in the plasticity resource and makes it possible to use large degrees of total deformation, which form increased strength properties.

It is known in the manufacture of high-carbon wire that the drawing operation is carried out to a total degree of deformation of 60-80% with a given unit degree of deformation for forming and reducing uneven deformation of the wire along its cross section (RF patent No. 2183523, B21C 1/00).

Both in the known and in the claimed method, the drawing operation with the choice of a single degree of deformation depending on the parameters of the deformation zone is also intended to obtain a uniform distribution of deformation over the entire cross section of the wire, providing an increase in the plastic properties of the wire.

However, in the inventive method, when choosing a single degree of deformation according to the claimed dependence, not only the working angle of the die is taken into account, but also the friction coefficient, the inclusion of which contributes to a simultaneous increase in the uniformity of the distribution of deformation over the cross section of the wire, the margin of plasticity and the ability to deform with large total compressions, which ensures obtaining high strength properties of the wire. In addition, taking into account the friction coefficient during drawing allows one to obtain compressive stresses in the surface layer of the wire, which further increase the level of plastic properties, as well as increase the resistance to brittle fracture, corrosion resistance, and wear resistance of the manufactured wire.

It is known wire drawing to a total degree of deformation of 60-95% to increase the strength properties of the wire (see I. Yukhvets. Production of high-strength wire reinforcement. - M .: Metallurgy, 1973, p. 63-66).

Both in the known and in the claimed method, the specified drawing mode is designed to create high strength properties of the manufactured wire.

Based on the foregoing, we can conclude that the inventive method of manufacturing wire does not follow explicitly from the prior art and, therefore, meets the condition of patentability "inventive step".

The invention is illustrated by drawings, where:

figure 1 schematically shows a production line for implementing the inventive method of manufacturing a wire;

figure 2 shows the focus of deformation during cold rolling of the original billet;

figure 3 shows the focus of deformation during wire drawing in a monolithic die.

A method of manufacturing a wire is as follows.

Cold rolling of the initial billet 1 (Fig. 1) is carried out sequentially in drive 2, non-drive 3 and then again in drive 2 rolls with a smooth barrel until an intermediate square section of the wire is obtained. In this case, the rolling of the workpiece 1 in each pass is carried out with a unit degree of deformation, which is determined depending on the corresponding diameter of the roll 4 from the condition:

where ε is the degree of deformation,

d is the size of the cross section of the workpiece, mm,

D is the diameter of the roll, mm

Cold rolling with the claimed modes provides an intermediate square section of the wire 5, in which plastic deformation penetrates the entire depth of the cross section of the workpiece. This is ensured by the fact that in the first pass, the rolling is carried out in horizontally mounted rolls 4, which creates in the side zones of the cross section of the workpiece 1, experiencing slight deformation, tensile stress. A change in the deformation pattern during the transition from the first to the second, from the second to the third stand activates the free sliding planes, creating favorable conditions for subsequent deformation and the formation of a uniformly distributed homogeneous deformed structure over the entire cross section of the workpiece 1. This leads to an increase in the plastic properties of the wire during cold rolling and at the same time creates the conditions for applying large total degrees of deformation and obtaining high strength properties in the subsequent process shorter tions.

After cold rolling, wire 5 is dragged in several passes through monolithic dies 6 (Figs. 1, 3) to a total degree of deformation of 85-95%. In this case, the wire drawing 5 is carried out with a unit degree of deformation, which is determined from the condition:

where α is the half-angle of the die, glad

ε is the degree of deformation,

f is the coefficient of friction in the deformation zone.

The half-angle α die 6 (Fig. 3), depending on the diameter of the wire 5 being manufactured, is set in the range from 3 to 7 degrees. The friction coefficient (f) when drawing the wire is set in the range from 0.03 to 0.1, depending on the type of lubricant coating and technological lubricants used in the drawing.

Wire drawing to the claimed total deformation degree of 85-95% provides a high strength properties of the wire by creating highly deformed (fragmented) structure in which the dislocation density exceeds 10 ¹⁰ cm ^-2. In addition, a change in the deformation scheme during the transition from cold rolling to drawing provides the activation of previously unused systems and slip lines, which helps to achieve a total degree of deformation of up to 85-95% without the formation of internal defects and premature loss of plastic properties of the wire. Also, the inventive drawing mode allows, by coordinating a single degree of deformation with a half-angle of the die α and the coefficient of friction (f) in the deformation zone, to create a uniform deformation along the cross section of the wire, which leads to a decrease in the residual tensile stresses in the wire and, accordingly, to a simultaneous increase in its strength and plastic properties. In addition, with such a drawing, compressive stresses arise in the surface layer of the wire, the presence of which leads not only to a significant increase in plastic, but also to an increase in the operational properties of the finished wire.

It is impractical to drag the wire to a total degree of deformation of less than 85%, since the strength properties of the wire being manufactured will be low due to the inability to create a highly deformed structure. Drawing a wire with a total degree of deformation of more than 95% is impractical, as this will lead to the formation of internal defects and cracks in the metal, and consequently to the loss of plastic and strength properties and its further destruction.

To substantiate the advantages of the proposed method for manufacturing wire in comparison with the prototype, six experiments were carried out, including experiments No. 1-5 by the present method, experiment No. 6 - by the prototype.

A blank in the form of a sorbitized wire rod made of steel 75 with a diameter of 6.50 mm was rolled with a single degree of deformation of 16 or 22% according to the claimed dependence, which was determined taking into account the diameters of the rolls of the drive non-drive stands, equal to 100 or 150 mm. Cold rolling was carried out to a total degree of deformation of 41 or 52%, respectively. Wire drawing was carried out with a single degree of deformation, which was determined by the claimed dependence. These data are given in the table. The drawing was carried out using technological lubricant BVS, the friction coefficient f when using which is 0.05. The working half angle of the monolithic dies was 4 °. Processing modes and test results are shown in the table.

The test results showed that the high-carbon wire manufactured by the present method (experiment No. 1-3), with high strength properties (2305-2395 MPa) has plastic properties 1.25-1.45 times higher than that of the prototype (experiment No. 6).

It is impractical to produce wire with modes beyond the declared limits, since low total reductions do not provide a high level of strength properties, and uneven deformation leads to a decrease in plastic properties (experiment No. 4), and when reductions above 95%, the steel loses its plasticity resource, cracks and defects form in it, which lead to frequent wire breaks during drawing (experiment No. 5).

Based on the foregoing, we can conclude that the inventive method of manufacturing a wire is workable and eliminates the disadvantages that occur in the prototype, which is confirmed by an example implementation of the method. The wire made by the present method has a complex of high strength and plastic properties.

Table Experience Number The diameter of the roll D, mm Workpiece diameter d, mm Diameter of the finished wire, mm Unit degree of deformation during rolling,% Unit degree of deformation during drawing,% The total degree of deformation,% Temporary tear resistance, MPa Yield Strength, MPa Relative extension, % Relative narrowing,% Number of twists Number of bends claimed one. one hundred 6.5 2.0 22 33 85 2305 1970 3.0 61 43 21 2. 150 6.5 2.0 16 37 91 2320 1975 3,5 62 44 21 3. 150 6.5 1.8 22 37 95 2395 2035 3.0 60 43 twenty four. one hundred 6.5 3.0 16 22 79 1780 1605 2,5 56 40 eighteen 5. 150 6.5 1,0 22 33 98 The wire did not fail due to frequent breaks prototype 6. one hundred 6.5 2.0 22 twenty 91 2250 2105 2.0 48 thirty 16

Claims (1)

A method of manufacturing a wire, including cold rolling the initial billet and subsequent drawing of the wire in monolithic fibers, characterized in that the cold rolling of the initial billet is carried out sequentially in drive, non-drive and then again in drive rolls with a smooth barrel with a single degree of deformation, determined from the condition

where ε is the unit degree of deformation during rolling; d is the size of the section of the workpiece, mm; D is the diameter of the roll, mm, to obtain an intermediate square cross-section of the wire, and wire drawing is carried out to a total degree of deformation of 85-95% with a single degree of deformation, determined from the condition

where ε is the unit degree of deformation during drawing; α is the half-angle of the die, rad; f is the coefficient of friction in the deformation zone.

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