RU2360755C1 - Pass sequence of tube-moulding mill - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: pass sequence contains matches of gauged horizontal rollers and dead vertical rollers, installed after each forming cage, and includes three two-high and one four-roll gauge. Stock tubes allows outer diametre D. Holes in rollers of the first gauge are implemented by circles of radius R₁=(0.495…0.50)·D. In the second and the third gauges holes are implemented as trapeziform, with lateral minor surfaces of the same radiuses, with major surface of the second gauge of radius R₂=1.6·D and similar surface of the third gauge with R₃=3.2·D. Breakout height of gauges into rollers is appropriately: H₁=(0.44…0.46)·D, H₂=(0.38…0.40)·D and H₃=(0.39…0.41)·D. Vertical rollers behind the first cage allows labor concave with radius r₁=R₁ behind the second cage - with r₂=R₂ and behind the third cage - with r₃=R₃ fourth finishing gage of system can be implemented with ability of dimensions changing by means of rearrangement in overall axial plane three rollers which are components of gauge.

EFFECT: invention provides receiving of thin-walled tube of square cross-section from round stock tube for minimum pass number.

2 cl, 1 ex, 2 dwg

Description

The invention relates to the processing of metals by pressure and can be used in the production of thin-walled pipes with a square cross section.

For the production of electric-welded pipes (mainly with a circular cross-section), continuous units are used, as described, for example, in A.A. Queen "Mechanical equipment of rolling and pipe shops", M., "Metallurgy", 1987, S. 395-398. The basic principles of calibration of rolls of pipe forming mills are given, for example, in the book of P.I. Polukhin and others "Rolling production", M., Metallurgizdat, 1960, pp. 894-898.

Known open forming calibers of a pipe-welding mill with variable diameters along their width and with a curvilinear generatrix of different radii at the barrel of the upper roll, the lower roll being made with a cylindrical groove in the middle of the barrel and with a curved generatrix of a given radius at the edges, and the parameters of the groove depend on the thickness of the walls of the formed pipes (see US Pat. RF No. 2204452, class B21C 37/06, published in BI No. 14, 2003). However, these gauges are not suitable for forming square pipes.

The closest analogue to the claimed object is a caliber system described in A.S. USSR No. 1391754, class B21C 37/08, publ. in BI No. 16, 1988

This system contains pairs of calibrated horizontal rolls and non-driven vertical rollers installed after each forming stand, and is characterized in that the rolls form open and closed gauges, and the rolls forming closed gauges are installed so that the bottom of each subsequent gauge in the course of molding above the bottom previous by the set value. The known gauge system is also unsuitable for producing square pipes from round ones.

An object of the present invention is the manufacture of thin-walled tubes of square cross-section from round tubes-blanks for a minimum number of passes.

To solve this problem, the proposed gauge system of the tube forming mill contains pairs of calibrated horizontal rolls and non-driven vertical rollers installed after each forming stand. For forming thin-walled tubes of square cross-section from round billets of external diameter D, the system contains three two-roll gauges and one four-roll with rolls located in the common axial plane, cuts in the rolls of the first caliber are made around circles of radius R ₁ = (0.495 ... 0.50 ) · D, and in the second and third calibers - trapezoidal, with small side surfaces of the same radii, with a large surface of the second caliber of radius R ₂ = 1,6 · D and a similar surface of the third caliber with R ₃ = 3,2 · D, while the height of the plunge calibers in rolls is respectively: H ₁ = (0.44 ... 0.46) · D, H ₂ = (0.38 ... 0.40) · D and H ₃ = (0.39 ... 0.41) · D, and the vertical rollers behind the first stand have working concave surfaces with a radius r ₁ = R ₁ , behind the second stand with r ₂ = R ₂ and behind the third stand with r ₃ = R ₃ ; the fourth finishing caliber of the system can be made with the possibility of resizing by moving in the common axial plane of the three components of the caliber rolls.

The given ratios of the parameters of the calibers were obtained empirically and are empirical.

The essence of the proposed technical solution is to optimize the size of the intermediate sections of the pipe being molded by creating double-roll gauges and vertical rollers of the appropriate configuration, which ensures the production of square pipes with a given geometry and for the smallest number of passes.

The invention is illustrated by drawings, where figure 1 schematically shows the proposed system of calibers (Roman numerals - serial numbers of calibers during molding). Figure 2 shows the vertical rollers located behind each stand with calibers I, II, III.

Gauges I ... III contain the upper 1 and lower 2 rolls of the same diameter D _B. In the rolls, circular grooves 3 are made with radii, respectively, of R ₁ , R ₂ , R ₃ and with a height (depth) of the insert H ₁ , H ₂ and H ₃ symmetrical with respect to the midline of the yy caliber, and the incisions in gauges II and III have the shape of a curved trapezoid, with side surfaces 4 of radius r ' ₂ = r' ₃ = (0.495 ... 0.50) · D, R ₁ = r ' ₂ = r' ₃ , R ₂ = 1,6 · D, R ₃ = 3.2 · D and H ₁ = (0.44 ... 0.46) · D, H ₂ = (0.38 ... 0.40) · D, H ₃ = (0.39 ... 0.41) · D .

Behind each stand with gauges I, II, and III, there are respectively vertical rollers 5, 6, 7 with concave working surfaces 8, the radii of which are: r ₁ = R ₁ , r ₂ = R ₂ and r ₃ = R ₃ .

The last IV gauge is a four-roll, formed by two horizontal rolls 9 and 10 and two vertical rolls 11 and 12, of which only horizontal rolls are driven. The working surfaces 13 of all the rolls are cylindrical.

During the operation of this system, the molded pipe passes all the calibers and the vertical rollers installed behind them in succession, while the last IV gauge includes a quadrangular section with convex faces of the required shape, which excludes deflection inside the walls of the finished square pipe.

A pilot test of the present invention was carried out at one of the pipe welding mills of OJSC Magnitogorsk Iron and Steel Works. For this purpose, the number of forming calibers and their parameters were varied, evaluating the results by the quality of the geometry of square pipes from 20 and 40 mm.

The best results were obtained using the proposed gauge system (high-quality pipes yield between 99.4 ... 99.9%). Deviations from the claimed parameters worsened the achieved indicators. So, in the presence of only three forming stands, it was not possible to obtain pipes with rectilinear sides of the section, and increasing the number of stands to 5 did not improve the geometry of the finished pipes, but increased production costs. The use of an IV two-roll caliber was not possible due to the private jams of the roll in the rolls.

The decrease in the values of R and r '(on the rolls) and r (on the vertical rollers) did not allow to obtain flat faces (they were convex), as well as the required radii of curvature on the finished profiles. A decrease in the values of H ₁ ... H ₃ led to the same result. An increase in R, r ', r, and H caused a deflection inside the faces of the square tube and a decrease in the radii of curvature in excess of the permissible deviations.

The caliber system, chosen as the closest analogue, was not used in the experiments due to its obviously unsuitability for achieving the goal. Thus, the experiments confirmed the acceptability of the technical solution found for forming high-quality pipes for a minimum number of passes and its advantage over a known object.

The feasibility study showed that the implementation of the present invention will reduce production costs by at least 12% with the required quality of thin-walled square tubes.

Concrete example

The gauge system of the tube mill has the form shown in figure 1. The diameter of the horizontal rolls D _in = 173 mm, vertical rollers D _p = 180 mm A square pipe with a thickness of 2 mm and a cross section of 25 × 25 mm with 2.5 mm rounding radii is formed from a round pipe with D = 31.3 mm.

System Parameters:

R ₁ = r'2 = r ' ₃ = 0.498 · D = 0.498 · 31.3≈15.6 mm; R ₂ = 1.6 · D = 1.6 · 31.3≈50 mm; R ₃ = 3.2 · D = 3.2 · 31.3≈100 mm; H ₁ = 0.45 · D = 0.45 · 31.3 = 14.1 mm; H ₂ = 0.39 · D = 0.39 · 31.3 = 12.2 mm;

H ₃ = 0.395 · D = 0.395 · 31.3 = 12.4 mm; r ₁ = R ₁ = 15.6 mm; r ₂ = R ₂ = 50 mm; r ₃ = R ₃ = 100 mm.

Diameter of horizontal rolls of IV gauge: D _g = 146.5 mm, vertical - D ' _in = 180 mm.

Claims (2)

1. The system of calibers of a tube-forming mill containing pairs of calibrated horizontal rolls and non-driven vertical rollers installed after each forming stand, characterized in that for forming thin-walled tubes of square cross-section from round billets of external diameter D, the system contains three two-roll calibers and one four-roll with rolls disposed in the common axial plane incisions in the rolls formed on the first gauge circle of radius R ₁ = (0,495 ... 0,50) · D , while the second and third calibers - gangway tsievidnymi with small lateral surfaces of the same radius and large caliber surface of the second radius R ₂ = 1,6 · D and large surface area of the third gauge radius R ₃ = 3,2 · D, wherein the height of the incision in the caliber rolls is respectively ₁ = H (0.44 ... 0.46) · D, H ₂ = (0.38 ... 0.40) · D and H ₃ = (0.39 ... 0.41) · D, and the vertical rollers behind the first stand are concave surfaces with radius r ₁ = R ₁ , behind the second stand - r ₂ = R ₂ and behind the third stand - r ₃ = R ₃ . 2. The gauge system according to claim 1, characterized in that the fourth finishing gauge of the system is configured to resize by rearranging in the common axial plane of the three rolls constituting the caliber.

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