RU2281178C1 - Concave sheet section - Google Patents

Abstract

FIELD: rolled stock production, possibly manufacture of cold bent sheet sections.

SUBSTANCE: concave bent section is made, mainly of steel with tension strength σ_B ≤ 630 MPa and with thickness S =0.7 - 2.5 mm. Section has lengthwise continuous corrugations with trapezoidal cross section and rounding radiuses between walls and horizontal portions of corrugations. Walls are inclined toward base of corrugations by angle 20 - 25° relative to their vertical axial line. Width of corrugation bases is less than width of their top portions. Height of corrugation h_r consists 0.8 -1.4 of their maximum width. Rounding radius R =( 3.5 - 4.0) S; spacing between corrugations t = (1.4 - 2.8) h_r.

EFFECT: enhanced consumer's properties of sections, lowered metal consumption for making them.

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Description

The invention relates to rolling production and can be used in the manufacture of cold-formed sheet profiles.

Such profiles are made on roll forming mills by sequential shaping of the corrugations, moreover, longitudinal continuous (through) corrugations have a very different cross-sectional configuration, which is due to the specific purpose of this profile. One of the common types of sheet corrugated profiles are profiles with trapezoidal corrugations.

Some types of corrugated profiles manufactured on modern mills are given, for example, in the manual edited by. I.S. Trishevsky "Production and application of bent profiles of hire", M., "Metallurgy", 1975, pp. 494-508.

Known sheet corrugated profile containing semicircular (wavy) corrugations and flanging along the lateral edges, directed in different directions at a certain angle (see US Pat. RF No. 1750780, CL 21 D 5/06 from 01/21/91). The disadvantage of this profile is its low stiffness in the transverse direction.

The closest analogue to the claimed object is a bent sheet profile with a trapezoidal corrugation of 1000 × 30 × 2 mm, given in GOST 9234 "Steel bent sheet profiles with trapezoidal corrugation".

This steel profile with a thickness of S = 2 mm contains continuous longitudinal corrugations and is characterized in that the corrugations are made with a trapezoidal cross section and with radii of curvature between the walls and horizontal sections of the corrugations, and the corrugation base is wider than their top. A drawback of such a profile is also its low transverse stiffness, which forces either to increase the thickness of the profile and the height of its corrugations (which leads to an increase in metal consumption, i.e., increases the consumption of metal to achieve the required stiffness of the profile), or requires the use of additional elements that reinforce its transverse rigidity.

An object of the present invention is to improve the consumer properties of bent sheet profiles and reduce their metal consumption by increasing the stiffness (load-bearing capacity) of these profiles.

To solve this problem, a bent sheet profile made mainly of steel with a tensile strength σ _of ≤630 MPa, thickness S = 0.7 ... 2.5 mm, with longitudinal solid corrugations made with a trapezoidal cross section and with with radii of curvature between the walls and the horizontal sections of the corrugations, these walls are inclined towards the corrugation bases and at an angle of 20 ... 25 ° to their vertical center line, and the width of the corrugation bases is less than the width of their vertices, while the height of the corrugations h _g is 0.8 ... 1.4 of their maximum width, for the sake of rounded mustache R = (3.5 ... 4.0) S, and the distance between the corrugations t = (1.4 ... 2.8) h _g .

The above relationships between the main profile parameters are obtained experimentally and are empirical.

The essence of the proposed technical solution lies in a fundamentally new form of corrugations and optimization of their parameters.

Indeed, for a well-known sheet profile, the width of the corrugated apex is less than the width of their bases, while for the proposed one, the opposite. As a result of this, firstly, the contact area of the horizontal sections of the profile increases, which reduces stresses in the metal when the profile is loaded during its operation. Secondly, as shown by experimental tests (see below), with the loss of stability by corrugations (due to heavy loads), the nature of their “settling” in the known and proposed profiles is completely different.

The crushing of corrugations of a known configuration begins with a change in the angle of inclination of their walls to the horizontal, which quickly leads to a warp and "flattening" of the corrugations. Corrugations of the proposed configuration, when their height decreases, at some point begin to “abut” each other with rounded sections of their peaks, as a result of which the crimping of the corrugations smoothly slows down, and the profile withstands a significantly greater vertical load.

The inventive bent sheet profile (cross section), as well as the configuration of its corrugations, are shown in the drawing (a, b).

A cross section of a profile of thickness S consists of trapezoidal corrugations 1 containing flat horizontal vertices 2 and inter-corrugated sections 3 conjugated by inclined walls 4, and the distance between solid corrugations along the profile width is t. The corrugations have a height h _g , the width of the apex b _g and the angle of inclination of the walls to the horizontal - α, and the width of the apex is greater than the width of the corrugation base, i.e. b _g > b _o . Places of junctions of 5 and 6 peaks and flat sections of corrugations with their walls are rounded with radii R. The edge sections 7 of the profile can be flat (see drawing - a) or with flanges (not shown); full profile width - V.

An experimental verification of the proposed sheet profile was carried out on models (in laboratory conditions) and directly on the profiles themselves, manufactured at the 0.5-2.5 mill of the Magnitogorsk Iron and Steel Works OJSC.

For this purpose, in all cases, profiles with different ratios of the above parameters, made of a steel billet with a thickness of 0.7 ... 2.5 mm with δ _in ≤630 MPa, were subjected _to upsetting on a press with recording of stress-strain diagrams. The greatest rigidity (resistance to vertical load) showed sheet profiles with the proposed corrugations. Deviations from the optimal values of the ratios of their parameters reduced the value of the ultimate load (before crushing the corrugations), and also changed the nature of the deformation of the corrugations.

So, with an increase in the angle α to 26 ... 40 °, the load of crimping the corrugations decreased by 3 ... 95%, and for α <20 ° the corrugations did not always “rest” against each other in sections 5, which accelerated them crushing (i.e., at the same load, it occurred more quickly in time).

When h _g : b _g <0.8, the stiffness of the profiles decreased, and when h _g : b _g > 1.4, the loss of stability by corrugations was accelerated. Similarly, an increase in R over 4S and a decrease: R <3.5S. A large value of t> 2.8 h _g also reduced the bearing capacity of the profile, and at t <1.4 _{h g the} corrugation of the corrugations on the roll forming mill.

The profile 1000 × 30 × 2 mm, taken as the closest analogue, showed in tests the bearing capacity, lower by an average of 80% compared with the claimed profile, which had the same height of the corrugations and formed from the same workpiece.

The advantages of the new profile were especially noticeable during dynamic tests, when corrugated sheets of both types served as a pallet (lining) under the load dropped from a height. At the same dump height, the claimed profile, firstly, withstood until its complete collapse, a load that was 2.5 times larger on average than the known profile. Secondly, the first of them kept intact even glass vessels with water used as cargo (up to certain limits of height and weight).

Thus, an experimental verification confirmed the acceptability of the technical solution found to achieve the goal and its advantages over a well-known object, selected as the closest analogue.

The technical and economic analysis carried out in the workshop of bent profiles of MMK showed that the metal consumption of the claimed profile will be less than that of the known one by at least 2 times (due to the possibility of using a thinner workpiece). It should be considered promising the possibility of using this profile when landing various cargoes as a damping pallet (for example, instead of brake parachutes).

Concrete example

The bent sheet profile with a width of B = 1050 mm is made of steel with a thickness of S = 1.6 mm with δ _in = 500 MPa and contains four trapezoidal corrugations (see drawing), the walls of which are inclined to the vertical yy at an angle α = 23 °. The main profile parameters: t = 210 mm; h _g = t: 2.1 = 210: 2.1 = 100 mm; b _g = h _g : 1.1 = 100: 11≈9.1 mm; R = 3.75 S = 3.75 · 1.6 <6 mm.

Claims (1)

Bent sheet profile, mainly made of steel with a tensile strength σ _B ≤630 MPA, thickness S = 0.7-2.5 mm, with longitudinal and continuous corrugations made with a trapezoidal cross section and with radii of curvature between the walls and horizontal sections of the corrugations characterized in that the walls are inclined towards the corrugation bases and at an angle of 20-25 ° to their vertical center line, and the width of the corrugation bases is less than the width of their vertices, while the height of the corrugations h _g is 0.8-1.4 of their maximum width , the radii of curvature R = (3.5 ÷ 4.0) S, and the races -being between corrugations t = (1,4 ÷ 2,8) h _r.