RU2761840C1 - Method and device for drawing square cross section wire in a roller die from a round workpiece - Google Patents

Abstract

FIELD: wire production.

SUBSTANCE: invention relates to the production of square-section wire in a roller die from a round-section workpiece. The workpiece is straightened, flattened and then dragged through a four-roller die. The flattening of the initial round-section blank is carried out in a pair of rollers with a closed gauge, the height of which is equal to the side of the square of the square-section wire, and the width exceeds the diameter of the initial workpiece by 0.08-0.20 mm.

EFFECT: as a result, labor intensity decreases and the stability of the drawing process of square- cross section wire increases, the resistance of the roller drawing increases.

3 cl, 3 dwg

Description

The invention relates to drawing production and can be used in the manufacture of square and rectangular wire in roller drags.

The method includes drawing, after appropriate preparation, a round wire through a four-roller die to obtain a square or rectangular wire in one pass.

The known method and device for drawing a square wire through a roller drawing from a round billet (Myshechkin A.A., Osadchiy V.Ya. Machines and technology of hardware production. Textbook - M., MGUPI, 2008, pp. 93-97). To obtain a given size, a round wire of a certain size after preliminary preparation (heat treatment, application of lubricating coatings) is pulled through a four-roller die, consisting of two pairs of rollers. A correct wire straightener is installed in front of the roller die.

The disadvantage of this method is the low durability of the rollers due to high contact pressures when drawing a wire of square, rectangular, trapezoidal cross-sections, used for the manufacture of spring washers from steel 65G, steel 70 with high resistance to plastic deformation.

The prototype of the invention is a method for the production of wire and tape of rectangular and square cross-section. The method consists in the fact that the workpiece, when drawing through a four-roller head, is deformed at each pass only in one of the mutually perpendicular directions by one pair of rollers pressed with a force exceeding the metal pressure and another pair of rollers, which only determine the size and accuracy of the product in this direction of deformation (Moiseev VF, Shilkov VB Method for the production of wire and tape of rectangular cross-section. USSR author's certificate No. 184796, B21s, published 07/30/1966, bul. No. 16).

The disadvantage of this method is the complexity of its implementation, since the resulting wire is pulled in several pulls through a four-roller die with a changeover. As a result, the drawing process is complex, laborious, has a low tool life and does not provide the required accuracy of the resulting profile.

The technical problem of the invention was to eliminate the disadvantages of the known technical solutions.

The technical result of the proposed invention is an increase in the accuracy of the resulting square profile, a decrease in pressure on the rollers and an increase in their durability, a decrease in the labor intensity of setting up and an increase in the stability of the process of drawing wire of square and rectangular sections.

The technical result is achieved by the fact that when drawing a square or rectangular wire through a four-roller die in front of a four-roller die, the initial round blank is first flattened to a size equal to the side of the square for a square wire or a smaller rectangular wire, and then pulled to the final size through a four roller die ... To increase the stability of the drawing process in a four-roller die and reduce the pressure on the rollers, the initial round billet is crimped in a pair of rollers with a closed groove. When drawing a square wire with a side of a square of 0.8-2.0 mm, the original round billet is crushed in a pair of rollers with a closed gauge, the height of which is equal to the size of the square, and the width exceeds the billet diameter by 0.08-0.20 mm. The rectangular groove increases the stability of the technological process and provides optimal conditions for the deformation of the crimped workpiece in the four-roller die.

To implement the proposed drawing method, a device is proposed, in which a flattening device is installed in front of the four-roller die for preliminary crimping of the round wire, consisting of two rollers. To ensure the stability of the drawing process, the diameter of one pair of rollers of a four-roller die should be greater than the diameter of the other pair of rollers by 20-40 mm of rollers.

When drawing a square wire with pre-flattening, a round billet in one pass is successively crimped in height between the rollers of the flattening device and then pulled through a four roller die to the finished size. Pre-flattening ensures the redistribution of deformations between the rollers of the four-roller die and, together with the force of pulling the workpiece through the straightening rollers, creates the necessary counter-tension. The essence of counter-tension lies in the fact that a force is applied to the pulled metal from the side of its entry into the drawing, directed in the direction opposite to the movement of the metal, and therefore called counter-tension. From this, tensile stresses are created in the strip even before it enters the drawing channel in the axial direction. They cause a change in the stress-strain state of the metal in the deformation zone, a decrease in the pressure of the metal on the walls of the die and its wear. The change in the stress-strain state during drawing with counter-tension can be explained by the condition of the plasticity of the metal in the deformation zone. Due to the fact that the condition of metal plasticity is unchanged, then with an increase, due to counter-tension, tensile stresses in the deformation zone along the drawing axis, a decrease in the second stress in the perpendicular direction occurs, i.e. reducing the pressure of the metal on the rollers (Myshechkin A.A., Osadchiy V.Ya. Research and improvement of the process of drawing a square steel wire with counter-tension // J. Steel, No. 8, 2019, pp. 47-51).

Due to the fact that during the patent information search and analysis of the proposed method, no technical solutions were found that have features similar to those that distinguish the proposed method and device from the prototype, the claimed technical solution meets the criterion of "significant differences".

To solve the problem, a method is proposed, in which, when drawing a square or rectangular wire through a four-roller die in front of a four-roller die, the initial round blank is first flattened to a size equal to the side of a square for a square wire or a smaller rectangular wire, and then pulled through a four roller die to the final size.

The essence of the proposed method and the device for its implementation is illustrated by drawings, which do not cover and, moreover, do not limit the entire scope of the claims of this technical solution, but are only illustrative materials of a particular case of implementation.

FIG. 1 shows a general diagram for the implementation of the proposed method of drawing

FIG. 2 shows a wire crimping device.

FIG. 3 shows a four-roll die for drawing square or rectangular wire.

The installation for implementing the proposed method includes a device for unwinding the original wire 1, a straightening device for straightening the original workpiece 2, a device for flattening, consisting of two rollers 3,4, a four-roller die, consisting of horizontal (narrow) 5 and vertical (wide) 6 rollers , devices for winding finished square or rectangular wire (take-up drum) 7. Position 8 denotes the wire after crimping (crimping), position 9 - finished wire after the roller die. First, the initial billet (wire of circular cross-section with a diameter D _ref ) is installed on the unwinding device 1, then it is passed sequentially through the straightening device 2, the device for crimping (3,4 flattening rollers) and then through the 5,6 rollers of the four-roller die. After that, the winding of the finished wire begins on the take-up drum 7.

In the flattening device, the original round billet is flattened to a size equal to the side of the square for a square wire or a smaller size of a rectangular wire. Experimental studies have shown that for the manufacture of spring wire with a side of a square 0.8; 1.0; 1.4; 1.6; 2.0 mm, corresponding to the requirements of GOST 11850-72, it is necessary to use a round annealed workpiece with a diameter of 0.96; 1.20; 1.70; 1.90; 2.40 mm respectively. These dimensions are the minimum to produce a square wire in a roller die. With the specified dimensions of the workpiece, a square profile is formed that meets the requirements of GOST 11850-72 and the necessary margin of safety is provided during drawing. If it is necessary to obtain wire with more stringent size requirements, the size of the workpiece can be increased by 0.05-0.20 mm (depending on the size of the square and the technological scheme). When the diameter of the workpiece is exceeded in excess of the recommended values, the drawing voltage increases, the pressure on the rollers, burr formation in the corners of the square is possible due to the overflow of the gauge and the wire breaks.

In the general case, the diameter of a round billet to obtain a given square can also be determined by calculation (Gulko V.I. Production of wire and profiles in roller trays / V.I. Gulko, V.A. Udmurtia, 1989 .-- 132 p.):

do = a / (1-0.01δ),

where: a - the value of the side of the square, δ - compression.

δ = 15.4 - 0.02K + 83.36 / K,

where: K is the fill factor of the gauge.

K = (R / a) 100%,

where: R is the radius of curvature of the edge of the square profile. In the calculations, the value of the radius is set from GOST 11850-72.

The study of the proposed process of drawing a square wire with a square side of 0.8-2.0 mm with preliminary crimping of the original workpiece to a size equal to the side of the wire square, showed that crimping allows reducing the metal pressure on less strong narrow horizontal rollers by 35-55% in depending on the side of the square compared to conventional drawing through a roller die. The metal pressure on wide vertical rollers increases by 10-15%. The nature of the pressure change on the horizontal and vertical rollers is explained by the fact that the main metal deformation occurs in the vertical rollers, which are adjusted with significant preliminary pressure to the side surface of the horizontal rollers.

When debugging the proposed process of drawing a square wire with a square side of 0.8-2.0 mm, it was found that in order to increase the stability of the technological process and reduce the pressure on the die rollers, it is advisable to subject the original circular section billet to a pair of rollers with a closed groove, the height of which is equal to the size square, and the width exceeds the diameter of the workpiece by 0.08-0.20 mm. In this case, the rectangular gauge of the crimping rollers increases the stability of the process and provides optimal conditions for the deformation of the crimped workpiece in the four-roller die. In fact, preliminary (rough) shaping of the square profile takes place in the flattening caliber, and the final shaping of the profile or its calibration takes place in the roller die. This improves the accuracy of the resulting square profile, reduces the pressure on the rollers and increases their durability.

The choice of the size of the original workpiece and the width of the rectangular groove in the crimping device must be selected taking into account the broadening of the workpiece during crimping. The degree of reduction along the height of a round billet when flattening the wire D = 0.96-2.40 mm to obtain a square wire with a side of a square 0.8-2.0 mm is about 17%. A study of the process of flattening a round billet with such a reduction in height shows that the broadening coefficient of the billet β ( β = b / d , i.e. the ratio of the width of the billet after crimping to its original diameter) is 1.06 - 1.10. Therefore, the width of the crimped workpiece is equal to:

b = β⋅d .

For example, when drawing a square wire with a square side of 1.4 mm from a workpiece with a workpiece diameter D1.7 mm, we have the following parameters. The reduction ratio when flattening the wire to a size of 1.4 mm is ε = 0.17. Next, we find the broadening coefficient β = 1.10 and the width of the workpiece after flattening b = 1.10 ⋅ 1.70 = 1.87 mm. Thus, the gauge width for a square wire with a side of a square of 1.4 mm must be selected in the range 1.82 - 1.90 mm. Studies of the process of drawing a square wire have shown that the ratio of the width of the gauge to its height when drawing a wire with a side of a square 0.8-2.0 mm should be in the range 1.30 - 1.36.

In the proposed drawing method (Fig. 3), narrow horizontal rollers 5 provide minimal wire deformation and control of the finished profile size, and wide vertical rollers with higher strength carry out the main metal deformation and bear the main load. At the same time, to ensure the stability of the drawing process and eliminate the turn of the crimped billet, the diameter of the narrow horizontal rollers 5 (D _g ) of the four-roller die must be 20-40 mm larger than the diameter of the vertical pair of rollers 6 (D _c). When wire drawing is square with a side of a square and 2.0 mm using horizontal rolls stepped shape with a diameter D _r = 160mm and a width running web, equal to the square side and vertical rolls _in a diameter D = 140 mm and 10-12 mm in width.

During debugging and experimental-industrial use of the proposed technology for producing a square wire with preliminary flattening in a closed caliber, it was found that the process of drawing a square wire was stable, the deviation of dimensions did not exceed half of the tolerance field. The wear of the rollers was uniform over the width of the working belt, the durability of the rollers increased. The results obtained indicate the feasibility of widespread use of this process in the production of square and rectangular wire.

Claims (3)

1. A method for the production of square wire in a roller die from a billet of circular cross-section, including straightening the billet and its drawing through a four-roller die, characterized in that before the four-roller die, the original billet of circular cross-section is subjected to crimping, and then the flattened billet is pulled through the specified four-roller die, when In this case, the flattening of the original workpiece with a circular cross-section is carried out in a pair of rollers with a closed groove, the height of which is equal to the side of the square of the wire of the square cross-section, and the width exceeds the diameter of the original workpiece by 0.08-0.20 mm. 2. Device for the production of square wire by the method according to claim 1, characterized in that it comprises an unwinding and straightening device, a four-roller die, a winding drum and a flattening device installed in front of the four-roller die, wherein the flattening device is made in the form of a pair of rollers with a closed gauge, the height of which is equal to the side of the square of the wire of square cross-section, and the width exceeds the diameter of the original workpiece by 0.08-0.20 mm. 3. The device according to claim 2, characterized in that the diameter of one pair of rollers of the four-roller die exceeds the diameter of the second pair of rollers by 20-40 mm.

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