RU2329884C1 - Method of wire drawing in rollers - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method includes a preliminary deformation of an ingot during several passes with vertical and horizontal rollers when after each pass a transitional square section of wire is obtained by means of changing the gap between the rollers. A final forming of a circular cross section of wire is performed by the scheme "oval-circle". The task is obtained due to a preliminary deformation of an ingot with rollers of oval shape grooves; the said grooves have regulated depth of a cut and a groove radius; at that the transitive cross section of wire has a shape of an arrow-headed square.

EFFECT: expanding of performance capabilities and upgrading quality of wire.

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Description

The invention relates to the field of metal forming, specifically to drawing and rolling production, and can be used in the manufacture of bars and wires of various, mainly round, cross-section using roller dies or rolling stands.

There is a known method of drawing, involving the production of round wire by deformation of the initial billet in dies with pairs of horizontal and vertical rollers offset along the drawing axis, the streams of which form respectively oval and round gauges (Krasavin B.N., Boyarshinov M.I., Polyakov M. G. The use of roller dies abroad. Series 9: Hardware production. Information No. 2. - M .: TsNIICHermet. - 1971. - C.11-16) - [1]. This drawing method is used, for example, to calibrate a hot-rolled wire (wire rod) as a rough operation, carried out before the traditional wire drawing in monolithic dies. The method allows to increase the efficiency of the process by reducing the cost of manufacturing a working tool, technological lubrication and preparation of the surface of the workpiece before drawing. A significant drawback limiting the wider application of this method is the difficulty of its use in multi-pass drawing, since obtaining a specific wire size requires the manufacture of an appropriate set of working rollers, including four rollers, and with continuous multi-pass drawing, a fleet of roller dies of at least equal to the number of passes on the route. This significantly increases the cost of manufacturing a working tool, and due to the loss of time for setting up and replacing dies, the productivity of the process decreases.

Another well-known option for roller drawing of round wire is a method that involves the use of the oval-oval caliber system at the preliminary stage, with the last pass being carried out according to the oval-circle scheme (Gulko V.I., Voitsekhovsky V.A., Grigoryev AK Production of profiles and wire in roller dies. - Izhevsk: Udmurtia, 1989. - P.67). However, the introduction of such a calibration is associated with a number of difficulties associated primarily with the inability of the existing drawing equipment to work with an intermediate oval cross-section of the wire.

In the processing of low-plastic materials, a method for producing round sections is also used, which provides for preliminary deformation of the round section of the workpiece in multi-roll calibers in the form of a lancet square, with final deformation in a round multi-roll caliber (Polyakov M.G., Nikiforov B.A., Gun G.S. Deformation of metal in multi-roll calibers. - M .: Metallurgy, 1979. - P.87-88). The implementation of this method requires a large fleet of working tools, since each cross-section requires a specific multi-roll caliber formed by four rolls (in the case of drawing by rollers), the manufacture and adjustment of which is associated with significant costs.

There is also a known drawing method, which is the closest analogue and provides for multi-pass production of round wire in roller dies with offset pairs of rollers in two stages (Vydrin A.V., Shter A.A., Popov Yu.N., Barichko B.V. the efficiency of drawing processes in roller drafts. // Proceedings of the Fifth Congress of Rollers. - M.: Chermetinzhiniring. - 2004. - P.385-387) - [2]. According to this method, at the first stage, in several passes, the initial workpiece is deformed on a smooth barrel (non-caliber drawing) to produce a square cross-section in each pass, after which, at the second stage, the final square cross-section of the wire is deformed into an oval-circle pattern into a wire round section. Obtaining intermediate square sections is provided by one set of non-calibrated rollers due to the sequential (from passage to passage) change of technological gaps between them. This method of drawing provides an increase in the efficiency of the technological process, since to obtain a finished round cross-section of the wire, only two roller dies are required: one with a set of uncalibrated rollers, and the other with a set of rollers profiled according to the oval-circle pattern.

The considered technical solution has a number of disadvantages that limit its effective use. Obtaining a transitional cross-section of the wire in the form of a square with repeated drawing at the vertices of the section is associated with the formation of sharp edges. These edges are stress concentrators and, as a rule, the place of crack formation. This circumstance makes it impossible to process low-plastic metals, bimetals and composite materials, prone to cracking or delamination and requiring smooth contours of the cross section during deformation, that is, it limits the range of processed materials. In addition, the sharp edges of the cross section cause sunsets during subsequent drawing according to the "oval-circle" pattern, make it difficult for the wire to slide along the conical portion of the drawing drum (in the case of conical drums) and contribute to the rapid wear of the drawing drum. Another significant drawback of the known method is that the square shape of the cross section is not advantageous when moving to an oval-circle drawing due to the significant unevenness of deformation and the lack of centering of the square section in the oval gauge. The consequence of this drawback is a decrease in the accuracy of the resulting round wire. In addition, the deformation scheme "square billet - oval caliber" is characterized by increased wear of the rollers with oval-shaped streams.

The invention is based on the technical task of eliminating these drawbacks, namely, expanding the technological capabilities of the known method of drawing in roller dies and improving the quality of the resulting wire.

To do this, in the known method of drawing wire in roller dies, including pre-deformation of the workpiece in several passes by vertical and horizontal rollers to obtain in each pass a transition square cross-section of the wire, provided by changing the gap between the rollers, and the final formation of a circular cross section of the wire according to the oval-circle pattern ", The preliminary deformation of the workpiece is carried out by rollers with oval-shaped streams made with a groove depth of the stream Н _Р = 0.5D _G and a radius equal to

where D _Z - the diameter of the original workpiece; D _G - the diameter of the finished wire.

The value of the depth of cut and the radius of the creek of oval caliber determine the shape of the resulting lancet square section and have an optimal value determined by the relations

и Н_Р=0,5D_Г

and N _P = 0.5D _G

повышает вероятность образования острых кромок при вершинах квадратного сечения, получаемого на этапе предварительной деформации, что явно нежелательно. Выполнение ручья овального калибра радиусом

может привести к переполнению овального калибра, то есть появлению закатов на поверхности проволоки.Running a creek of oval caliber radius

increases the likelihood of sharp edges at the vertices of the square section obtained at the stage of preliminary deformation, which is clearly undesirable. Running a creek of oval caliber radius

can lead to overflow of the oval caliber, that is, the appearance of sunsets on the surface of the wire.

Performing a depth of cut of a stream of H _P > 0.5D _G does not provide the required calculated cross-section of a pre-finished lancet square, and performing a depth of cut of a stream of H _P <0.5D _G leads to an oval gauge overflow, which entails the appearance of sunsets on the wire surface .

The use of a lancet square as an intermediate section during a non-gauge drawing at the stage of preliminary deformation allows avoiding the formation of sharp edges at the vertices of the intermediate section of the wire, which in turn provides improved quality of the round wire (due to the absence of sunsets on the metal surface) and expands the range of grades products (by reducing the likelihood of cracks in the places of formation of sharp edges of the intermediate section of the wire and the possibility of rabotki maloplastichnyh prone to cracking of metals and alloys). In addition, the rounding of the sides of the square section obtained at the stage of preliminary deformation reduces the unevenness of deformation according to the "oval-circle" scheme at the second stage of the technological process, which improves the accuracy of the obtained round section of the wire, that is, its quality, and increases the life of the rollers with oval caliber in the finishing transition.

The proposed method allows to stabilize the position of the wire in the deformation zone (centers the profile on the barrel of the roller) and reduces the likelihood of transverse (along the length of the barrel of the rollers) movement of the metal, which was characteristic of the known method of drawing [2] and required additional costs to eliminate this phenomenon (using box gauges, creation of anti-tension, changing the design of guide valves).

The advantages of the proposed method should also include the possibility of its implementation in reverse mode, which reduces the cost of working time for the preparation and refueling of the wire in the drawing machine, as well as the installation and removal of riots with a single drawing.

The claimed technical solution is illustrated by drawings, where Fig. 1 shows a diagram of a preliminary deformation step according to the proposed drawing method in roller dies, Fig. 2 is a section A-A in Fig. 1, Fig. 3 is a section B-B in Fig. 1, figure 4 is a General technological scheme of the proposed method of drawing in roller dies.

. Две другие стороны квадратного сечения 4 предварительно сформированы ручьями горизонтальных роликов 2, которые также выполнены радиусом R_P. Получение квадратного сечения проволоки обеспечивается определенной величиной рабочих зазоров δ₁ и δ₂ между роликами.The proposed method is as follows. The front end of the original billet 1 (Fig. 1), for example, of circular cross section is subjected to sharpening, passed sequentially through the space formed by the oval streams of horizontal 2 (Fig. 2) and vertical 3 (Fig. 3) rollers and captured by a pulling device. By applying to the front end of the pulling force T, the workpiece 1 is pulled through two pairs of rollers to obtain a metal section emerging from the die in the form of a pointed square 4 (Fig. 3) with sides of dimensions a ₁ . Two sides formed by streams of vertical rollers 3 are made with a radius

. Two other sides of square section 4 are preformed by streams of horizontal rollers 2, which are also made of radius R _P. Obtaining a square cross section of the wire is provided by a certain value of the working clearances δ ₁ and δ ₂ between the rollers.

After the drawing is completed, the gaps δ ₁ and δ ₂ between the rollers are reduced and the resulting intermediate wire cross section in the form of a lancet square a ₁ × a _{2 is} drawn to the smaller size of the lancet square a ₂ × a ₂ (figure 4).

The described operations are repeated until a wire with a calculated cross section of the final lancet square a _n × a _{n is} obtained, thereby preforming the workpiece in n passes (Fig. 4). After that, the final deformation of the final clean lancet square section with dimensions a _n × a _{n is} performed according to the oval-circle pattern in one pass (Fig. 4), resulting in a round wire with a diameter of D _G. These operations of preliminary and final deformation can be performed simultaneously, for example, in the case of implementing the method on a machine for multiple wire drawing.

An example implementation of the proposed method.

Standard route for wire drawing of 2.0 mm diameter from a wire rod of titanium alloys VT1-0, VT16 with a diameter of 6.5 mm using a VR-2 / 2.125 roller die (conditional diameter of rollers - 125 mm), developed for the drawing section of Verkhne-Saldinskoye OJSC metallurgical production association ", as follows

⌀6.5 mm → ⌀6 mm → ⌀5.5 mm → ⌀5 mm * → ⌀4.5 mm → ⌀4.1 mm →

→ ⌀3.7 mm * → ⌀3.3 mm → ⌀3 mm * → ⌀2.7 mm → ⌀2.5 mm * →

→ ⌀2.2 mm → ⌀2 mm.

The route contains 12 passes. When drawing the VT1-0 alloy, annealing is not provided, and when drawing the VT16 alloy, annealing to remove hardening is performed after the third, sixth, eighth and tenth passes - are marked with an index (*) on the diagram. The tool park includes 48 rollers (one set). When implementing this route, the use of the oval-circle roller calibration scheme is envisaged, that is, essentially, the use of the method [1]. Design capacity - 24.5 tons of finished wire per year.

To intensify the process, a variant of the drawing route was proposed, providing for preliminary deformation of the workpiece using a non-caliber drawing according to the method [2], while the transitional sections of the wire had a square shape. The drawing route was focused on the equipment complex and the initial blank described above, and looked as follows:

- 1 stage (draft drawing in offset pairs of smooth rollers):

⌀6.5 mm → 5.0 × 5.0 mm * → 4.2 × 4.2 mm * → 3.7 × 3.7 mm * →

→ 3.3 × 3.3 mm * → 2.9 × 2.9 mm * → 2.6 × 2.6 mm * → 2.3 × 2.3 mm * →

→ 2.0 × 2.0 mm *.

- 2 stage (drawing according to the oval-circle calibration scheme):

2.0 × 2.0 mm → 02.0 mm.

This route contains eight rough and one final pass. VT 1-0 alloy was dragged without annealing, VT 16 alloy was dragged with annealing after each pass. The route required eight rollers (four with a smooth barrel, two with oval-shaped streams, two with round-shaped streams). The transition cross sections of square wire were obtained on one set of rollers by changing the gaps between them. Estimated productivity - 38 tons of finished wire per year. During industrial testing of this method, when drawing the VT1-0 alloy, a significant drawback was revealed - the appearance of sunsets on the finished wire, while the deviations in the cross-sectional dimensions were ± 0.05 mm. During the drawing of the VT16 alloy, intense cracking was observed at the edges of the transition section, which led to massive wire breaks at the stage of preliminary deformation and, ultimately, did not allow to obtain a finished wire section with a diameter of ⌀ 2.0 mm. Thus, the above disadvantages did not allow to implement the known drawing method for VT16 alloy and did not ensure the quality of the finished wire when drawing VT1-0 alloy in real production conditions.

To check the proposed method of drawing, a drawing route was developed and tested, providing for rough drawing of the workpiece in rollers with oval-shaped streams. In this case, the cross sections of the wire had the shape of a lancet square (SC).

- 1 stage: ⌀6.5 mm → SK (5.3 × 5.3) mm → SK (4.5 × 4.5) mm * →

→ SK (3.9 × 3.9) mm → SK (3.4 × 3.4) mm * → SK (3.05 × 3.05) mm * →

→ SK (2.8 × 2.8) mm * → CK (2.5 × 2.5) mm * → SK (2.3 × 2.3) mm * →

→ SC (2.1 × 2.1) mm *.

- 2 stage (drawing according to the oval-circle calibration scheme):

SK (2.1 × 2.1) mm → ⌀ 2.0 mm.

The technology based on the proposed drawing method provides for nine roughing and one finishing pass. The VT1-0 alloy was dragged without annealing, the VT16 alloy with seven anneals (marked *) at the stage of preliminary deformation. Estimated productivity - 35 tons of finished wire per year. The technology was tested and used at the drawing section of OJSC Verkhne-Salda Metallurgical Production Association. A billet with a diameter of 6.5 mm from VT1-0 and VT16 alloys was deformed in the VR-2 / 2.125 roller die into a final section of a wire with a diameter of 2.0 mm. The radius of the oval creek of the rollers at the stage of preliminary deformation was 6.85 mm, the depth of cut of the creek was 1.0 mm. The minimum required fleet of rollers to provide technology is 8 rollers. The volume of the experimental batch was 150 kg.

The proposed method of drawing provided the finished wire from alloy VT16, that is, expanding the technological capabilities of the known method, selected as the closest analogue. In favor of the new method is the fact that the quality of the obtained wire from VT1-0 alloy has increased significantly: cracks and sunsets were absent, and the accuracy of the obtained cross section increased. So, the maximum deviations of the dimensions of the finished wire with a diameter of 2.0 mm did not exceed ± 0.04 mm.

Claims (1)

The method of wire drawing in roller dies, including preliminary deformation of the workpiece in several passes by vertical and horizontal rollers, by changing the gap between them, to obtain a transition square cross-section in each pass, and the final formation of an oval-round circular wire, different the fact that the preliminary deformation of the workpiece is carried out by rollers with oval-shaped streams made with a groove depth of the stream H _p = 0.5D _G and a stream radius equal to

where D _Z - the diameter of the original workpiece; D _G - the diameter of the finished wire.

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