RU2346774C2 - Method for dressing of equal channel - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: in dressing of equal double-layer channel, edges of wider lower strip flat work are bent so that it embraces lateral edges of upper strip with specified angles of bending in the first, second, last but one and last passes with provision of total angle of its edges bending equal to 180°. Starting from the second stage, two strips are bent simultaneously and serially in passes at specified angles to arrange the right angle between flanges and walls of channel with specified radiuses of bending places and with specified maximum value of bending angle per stage.

EFFECT: higher quality of double-layer equal channels.

4 cl, 1 dwg, 1 ex

Description

The invention relates to rolling production and can be used for profiling equal-shelf two-layer channels.

High-quality bent profiles (including channel profiles) are made by sequentially bending the strip billet in the stands of the profile bending mill. The technology for the production of bent channels is described in sufficient detail, for example, in a book under the editorship of I.S. Trishevsky "Production of bent profiles (equipment and technology)." M .: Metallurgy, 1982, p. 243-250.

The main parameters of the channel profiling process are the values of the bending angles in one pass and the radii of the bending places, and the minimum angles and radii are taken in the last (finishing) passes.

A known method for the production of a bent channel profile, in which the bend of its wall in the first pre-passage is carried out by turning half of the wall associated with the larger shelf of the channel, clockwise in a vertical plane, and the return to its original state is carried out in the second pre-passage, while simultaneously turning against clockwise the second half of it at the same angle with the bending of the minor and the bending of the larger profile flange to the mentioned angle (see US Pat. RF No. 2040996, class B21D 5/06, publ. in BI No. 22, 1995). However, this method is suitable for profiling only asymmetrical channels.

The closest analogue to the claimed method is a method for profiling equal-channel channels according to US Pat. RF № 2164186, class B21D 7/00, publ. in BI No. 8, 2001

This method of profiling by sequentially bending the channel shelves at predetermined angles to obtain a right angle between the shelves and the wall of the profile and with the specified radii of the bending places is characterized by the fact that the workpiece is passed between the rollers installed with different gaps in separate passes, the value of which is determined by the size of the channel and tensile strength of the workpiece. The known method is not acceptable for obtaining two-layer channels formed simultaneously from two strips superimposed on one another.

Strips can have different thicknesses and be made of different grades of steel; the lower strip is of greater width, since its edges during molding cover the lateral edges of the upper strip, forming castle joints.

An object of the present invention is to provide high-quality two-layer equal-channel channels.

To solve this problem, in the method of profiling an equal-hollow two-layer channel, including bending the edges of a wider lower strip billet with grasping the lateral edges of the upper strip in the first pass, the bending angles of which are taken to be 30 °, in the second pass - 25 °, and in the penultimate and last passages - at 5 ° to ensure a total angle of bending of its edges equal to 180 °, from the second pass, bending of two strips simultaneously at the specified angles is carried out sequentially along the passages until a right angle between shelves and profile wall, with specified radii of bending places and with a maximum value of the bending angle per pass equal to 14 °; the value of the radius radii of the edges of the lower strip in all the passages is assumed to be the same and equal to (1.65 ... 1.70) S _H , where S _H is the thickness of the lower strip, mm; the bending radius when bending the shelves of the channel is reduced along the passages from R = (5.3 ... 5.5) · (S _H + S _B ) to R = (1.0 ... 1.1) S _H , where S _B is the thickness of the upper strips, mm; the total number of forming passes is ten.

The above process parameters are obtained empirically and are empirical.

The essence of the proposed technical solution is to optimize the values of the bending angles and bending radii during molding, which provides high-quality (primarily in geometry) two-layer equal-channel channels. Such channels can be made of cold-rolled strip billets of different thicknesses and mechanical properties, which allows us to vary the consumer properties of these profiles in a fairly wide range.

The proposed method is illustrated by the diagram in the drawing (Roman numerals - numbers of forming passes).

In the first pass, the bending of the side edges 1 of the lower strip 2 begins at an angle α ₁ = 30 ° with a bending radius r = (1.65 ... 1.70) S _N , which remains constant in all passes. In the second pass, the bending of the edges 1 by an angle α = 25 ° (i.e., α ₂ = α ₁ + Δα = 55 °) continues and the bending of the shelves 3 (i.e., the lower strip 2 and the upper 4 at the same time) begins at an angle β ₁ , and the bending radius R ₁ = (5.3 ... 5.5) · (S _H + S _B ).

In subsequent passes, the value of the radius of the places of bending between the shelves 3 and the wall 5 of the formed channel is successively reduced to R = (1.0 ... 1.1) · S _B in the penultimate (IX) and last (X) passes. The value of the bending angle β of the shelves varies along the aisles, not exceeding the maximum value Δβ = 14 ° (in our case, in the V passage). The bending angles of the edges 1 of the lower strip have a minimum value of Δα = 5 ° in the IX and X passes, and the formation of locking joints 6 on the edges of the channel shelves end in the last pass at α ₁₀ = 180 °. Thickness edges sill is obvious, h = 2S + S _{B H.}

Before starting the simultaneous molding of two strips, they are centered symmetrically to the midline of the yy gauge, which ensures equality of the side sections 1 of the lower strip, covering the edges of the upper strip 2.

Experimental verification of the proposed method was carried out on a roll forming unit 2 ÷ 8 × 100 ÷ 600 OJSC "Magnitogorsk Iron and Steel Works".

For this purpose, when profiling cold-rolled strips with a thickness of 2.0 ... 3.5 mm from different steels with a tensile strength σ _B = 400 ... 480 MPa, the parameters of the proposed technology were varied, evaluating the results by the quality (geometry) of the obtained two-layer equal-channel channels. The best results (yield of quality profiles within 99.2 ... 99.8%) were obtained with the implementation of the proposed method of profiling, and deviations from its recommended parameters worsened the achieved indicators.

Thus, an increase in the angles of bending of the edges of the lower strip in the I and II pass over, respectively, 30 ° and 25 ° led to the formation of cracks at the bending points, and a decrease in the values of these angles, without improving the geometry of the profiles, led to an increase in the total number of passes, i.e. . to an unjustified increase in the expense of expensive rolls. Similar results were obtained with bending angles in the IX and X passes α> 5 ° and α <5 °.

Profiling of two bands simultaneously, starting from the third pass, also led to an increase in the number of passes. At a maximum value for the passage Δβ> 14 °, crack formation on the outer sides of the bending places (between the shelves and the channel wall) of the lower strip is noted on individual profiles.

The method parameters listed in 2 ... 4 p.p. claims may differ when using blanks of other thicknesses and with other mechanical properties (σ _{B В} 400 ... 480 MPa).

The profiling technology, taken as the closest analogue, was not tested in experiments due to its unacceptability for the production of two-layer channels. Thus, an experimental verification confirmed the acceptability of the technical solution found to achieve the goal and its advantage over a known object.

Using the claimed invention on high-quality roll-forming mills similar to the unit 2 ÷ 8 × 100 ÷ 600 OJSC MMK (that is, equipped with two uncoilers)? will allow the production of two-layer channel profiles with enhanced consumer properties and increased rigidity (bearing capacity).

Concrete example

An equal-flange channel with H = 110 and B = 60 mm 6 mm thick (see Fig. 1) made of steel with σ _B = 440 MPa is profiled in 10 passes from cold-rolled strips with a thickness of S _H = 2.7 mm and S _B = 3, 3 mm wide 241.5 mm (lower strip) and 195 mm (upper).

Bending angles Δα of the edges of the lower strip (up to α = 180 °): 30 ° → 25 ° → 15 ° → 20 ° → 20 ° → 20 ° → 20 ° → 20 ° → 5 ° → 5 °.

Angles of bending Δβ of channel shelves: 10 ° → 10 ° → 12 ° → 14 ° → 13 ° → 11 ° → 10 ° → 8 ° → 2 °.

The value r = 1,675 · S _Н = 1,675 · 2,7≈4,5 mm.

The value of R ₁ = 5.4 · (S _H + S _B ) = 5.4 · 6≈32.5 mm; R ₁₀ = 1.05 · S _B = 1.05 · 3.3≈3.5 mm.

The thickness of the edges of the shelves of the finished channel: h = 2S _Н + S _В = 2 · 2.7 + 3.3 = 8.7 mm.

Claims (4)

1. A method for profiling an equal-hollow two-layer channel, including bending the edges of a wider lower strip billet with grasping the lateral edges of the upper strip in the first pass, the bending angles of which are taken to be 30 °, in the second pass - 25 °, and in the penultimate and last passes - 5 ° with the provision of a total angle of bending of its edges equal to 180 °, the implementation from the second pass sequential in the bendings of the bending simultaneously of two strips at predetermined angles to obtain a right angle between the shelves and the wall of the pro I fixed radius bending seats and a maximum angle hems for the passage of 14 °. 2. The method according to claim 1, characterized in that the value of the radii of the bending of the edges of the lower strip in all passages is assumed to be the same and equal to (1.65 ... 1.70) · S _H , where S _H is the thickness of the lower strip, mm 3. The method according to claim 1, characterized in that the bending radius when bending the channel shelves is reduced in passages from R = (5.3 ... 5.5) × (S _H + S _B ) to R = (1.0 ... 1 , 1) · S _B , where S _B is the thickness of the upper strip, mm. 4. The method according to claim 1, characterized in that the total number of forming passes is ten.