RU2288800C1 - Corrugated strip production process - Google Patents

Abstract

FIELD: plastic metal working, possibly manufacture of corrugated sheet rolled sections.

SUBSTANCE: process is realized due to shaping at successive passes corrugations with predetermined bending up angle beginning from strip mean portion. Angles of bending for each corrugation during successive passes are set equal to 25°→ 45°→ 65°→ 80°→ 90°. Strip is successively shaped till formation of corrugations having in cross section vertical walls, oval apexes and inter-corrugation portions. In two last passes corrugations are upset at inclining their walls outside to horizon due to applying to shaped strip crosswise mutually opposite forces in horizontal plane. In last but one pass walls ate inclined by angle consisting (1.17 -1.20)α and in last pass walls are inclined by angle α.

EFFECT: possibility for producing high quality sections with desired contour of cross section for minimum number of passes, lowered production costs.

2 cl, 2 dwg, 1 ex

Description

The present invention relates to the processing of metals by pressure and can be used in the manufacture of sheet corrugated profiles for hire.

Such profiles with longitudinal continuous corrugations of various cross-sectional configurations (semicircular, triangular, trapezoidal, etc.) are produced on multi-beam profile bending mills similar to the unit 0.5 ÷ 2.5 × 300 ÷ 1500 of OJSC Magnitogorsk Iron and Steel Works. Corrugations are formed by sequential profiling along the passes of forming, which consists in bending the corrugation elements at given angles and with given bending radii.

The technology of profiling corrugated sheets is described in sufficient detail in the book of I. S. Trishevsky et al. “Cold-formed corrugated profiles for hire”, Kiev, “Technika”, 1973, p.132-139. The most common system of sequential corrugation is the system in which corrugation is carried out starting from the middle of the strip width. This facilitates the profiling mode, simplifies the calculation of the width of the initial workpiece and technological transitions, and also facilitates the setup of the mill.

A known method of manufacturing corrugated bent profiles, including the simultaneous formation of corrugations in the rolls of the mill, with each pass the section of the workpiece is attached to a profile in which the distance from the point of contact of the rolls with the metal to the axis of rotation of the rolls is equal to that in the last forming stand (see.c. USSR No. 575156, class B 31 D 5/08 of 07/14/75). However, this method does not allow to obtain trapezoidal corrugations with a “reverse” inclination of their side walls (see below).

Closest to the claimed object is a method of manufacturing corrugated profiles (AS USSR No. 1174120, class B 21 D 5/06, published in BI No. 31, 1985).

This method consists in sequentially starting from the middle of the strip width, forming corrugations with predetermined bending angles along the aisles and is characterized by the fact that when forming corrugations of a trapezoidal shape, the upper base of the central corrugation in all aisles is located at the molding level, gradually lowering the flat interfacial sections from this level to a predetermined height, and the peripheral corrugations are molded by raising the upper bases to the molding level.

Such a profiling technology also does not allow obtaining trapezoidal corrugations with a “reverse” inclination of their side walls.

Indeed, as can be seen from figure 2, if you do not apply any special techniques, then in the calibers of the rolls of the roll forming mill it is possible to bend the side elements of the corrugations by no more than 90 °, i.e. make them upright.

The technical task of the present invention is to obtain high-quality profiles with the above cross-sectional shape for a minimum number of passes and reducing production costs.

To solve this problem, in a method for the production of corrugated strips, comprising corrugating sequentially through the corrugations, which is performed starting from the middle of the strip width to obtain corrugations with a given bending angle α, in contrast to the closest analogue, corrugations are formed with bending corners along the aisles for each corrugation equal to 25 ° → 45 ° → 65 ° → 80 ° → 90 °, until a molded strip of width B _{1 is} obtained with corrugations having vertical walls and oval peaks and interfacial sections in cross section, in two after In the last passes, the corrugations are shaped by settling them with the walls tilted outward to the horizontal with the application of transverse opposing forces to the formed strip in the horizontal plane, while in the penultimate pass, the corrugations are deposited to obtain an angle of inclination of their walls equal to (1.17 ... 1 , 20) α, and in the latter - to obtain a given angle of inclination α, and the width of the molded strip B ₁ when the corrugation is upset is reduced to B ₂ = (0.90 ... 0.95) B ₁ .

The essence of the proposed technical solution consists, firstly, in the formation of corrugations with vertical walls and oval peaks and interphore sections for a minimum number of passes, and secondly, in the sediment of the corrugations obtained with the desired slope of their walls. In this case, the bending angles in one pass are up to 25 ° (the known method has no more than 12 °). In addition, to prevent broadening of the deposited corrugated strip with the formation of “ordinary” trapezoidal corrugations (that is, with the side walls tilted toward the middle longitudinal plane of the corrugation), counter-directed forces are provided to the bottom of this strip. Such forces can be created, for example, by a corresponding notch of the lower rolls of the last two stands or by making shallow grooves on them around the circumference of the barrels.

The proposed ratio of the angles (α ₁ and α ₂ ) of the inclination of the walls of the corrugations in the last two passages ensures uniform wear of the rolls of the last two stands, which extends the work campaign of all the rolls between transhipments (rolls are dumped when the excess allowable rate of even one of them is worn).

Figure 1 schematically shows the sequential shaping of the corrugations (given the first five and last three passes), and figure 2 is a cross section of the finished profile (Roman numerals are the numbers of passes).

In the aisles I-IV, the formation of the inner (the vertical walls of the yy walls 1 of the two middle corrugations and the oval interfacial section 2 takes place). In the V passage, the walls 1 are bent to 90 ° and the formation of the outer walls 3 and oval vertices 4 of these corrugations with the angle of the wall bending begins 25 °. The formation of the middle corrugations ends in the 9th passage (not shown), where the bending begins at a 25 ° angle of the inner walls of the next two corrugations, and the formation of their outer walls begins in the 13th passage (not shown) and ends in the 17th bypass.

Corrugation is carried out in the XVIII and XIX passes to obtain the desired configuration of the corrugations shown in figure 2. In this case, a certain decrease in the width B _{1 of the} strip to the width B ₂ = (0.90 ... 0.95) B ₁ occurs. Knowledge of the narrowing of the strip is necessary when calculating the width of the original workpiece.

Experimental verification of the proposed method was carried out on a roll forming unit 0.5 ÷ 2.5 × 300 ÷ 1500 OJSC "Magnitogorsk Iron and Steel Works".

To this end, the bending angles per passage (and the total number of passes) were varied, the vertical draft (with a change in the angles α ₁ and α ₂ - see Fig. 1), the value of the final angle α ₂ (within 60 ° ... 70 ° ), as well as the quantity B ₂ → f (B ₁ ). The experimental results were evaluated by the quality (geometry) of the obtained corrugated profiles and by the number of passes required to obtain them.

The selected value of the final (predetermined) angle of inclination of the walls of the corrugations of the finished profile is optimal in the aspect of operating the profile: at α> 70 °, the “depreciation” properties of the profile deteriorate (with its dynamic load), and at α <60 ° the profile stiffness (its resistance profile bending) becomes insufficient.

The best results (high-quality output, i.e., fully meeting the requirements for geometry, profiles formed in 19 passes) were obtained with the implementation of the proposed technology. Deviations from its main parameters worsened the results.

So, an attempt to increase the bending angles per pass with a decrease in the total number of passes to 15 due to the appearance of unacceptable waviness in the inter-ridge sections failed. A decrease in the bending angles per pass (with an increase in the number of passes) did not improve the geometry of the profiles, but increased the consumption of rolls (and labor) by almost 25%.

Similarly, it did not improve the quality of the finished profiles and the draft of the corrugations in three passes (with a total of 20). The draft of the corrugations in one pass led to the curvature of their vertical walls and to irreparable transverse deflection of the profiles.

The change in the ratio between the angles α ₁ and (in either direction) α ₂ (in either direction) caused their uneven wear.

Positive results were obtained both from the “rough” notch of the rolls (R _a = 6 ... 9 μm), and the implementation of the two last stands of the mill of the above-mentioned radial grooves on the barrels of the lower rolls. The bandwidth after precipitation was within the range of B ₂ = 355 ... 365 mm (B ₂ = 385 mm).

The method of profiling corrugated strips, selected as the closest analogue, was not used in the experiments because of its unsuitability for obtaining the required profiles. Thus, a pilot test confirmed the acceptability of the technical solution found to achieve the goal.

According to the results of the feasibility study carried out at OJSC MMK, the use of the proposed method for the production of the above-described corrugated profiles will allow them to be obtained for the minimum number of passes with a decrease in roll consumption and production costs by at least 20%.

Concrete example

The corrugated profile with a thickness of S = 1.5 mm (see FIG. 2) and a width of B = 356 mm has four trapezoidal corrugations with H = 27, l = 51 mm, α = 65 ° and r = 5 mm.

The profile is formed from a workpiece with a cross section of 560 × 1.5 mm ² in 19 passes with bending angles during the formation of corrugations, starting from the middle of the strip width, equal to: 25 ° → 45 ° → 65 ° → 80 ° → 90 ° (see figure 1 ) The number of forming passes 17.

In the XVIII and XIX passes, the corrugations are deposited to obtain the angles of inclination of their walls to the horizontal, respectively 77 ° and 65 °. The width of the strip before the draft is B ₁ = 385 mm, after: B ₂ = 0.925 V ₁ = 0.925 385≈356 mm = B.

The radii R of the oval peaks and lower interphore sections are 17 mm.

The lower rolls of the last two stands have a barrel surface with Ra = 7.5 μm.

Claims (2)

1. A method for the production of corrugated strips, comprising corrugating corrugating sequentially in passes, which is carried out starting from the middle of the strip width, to obtain corrugations with a given bending angle α, characterized in that the corrugations are formed with bending angles in the aisles for each corrugation equal to 25 ° → 45 ° → 65 ° → 80 ° → 90 ° to obtain a molded bandwidth B ₁ with corrugations having a cross-sectional vertical walls and top and oval mezhgofrovye areas in the last two passes shaping Gough s are produced by their upsetting with the walls tilted outward to the horizontal with the application of transverse opposing forces to the formable strip in the horizontal plane, while in the penultimate pass, the corrugations are upset to obtain an angle of inclination of their walls equal to (1.17-1.20) α, and in the latter - with obtaining a given angle of inclination α. 2. The method according to claim 1, characterized in that when the corrugation is deposited, the width of the molded strip B _{1 is} reduced to B ₂ = (0.90-0.95) B ₁ .

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