RU2115499C1 - Method for making bent different-flange angles - Google Patents

Abstract

FIELD: plastic metal working, namely, manufacture of cold bent rolled sections. SUBSTANCE: method comprises steps of successively from pass to pass bending up members of strip blank with thickness 0.7-2.5 mm for making equal-flange channel section and for subsequently developing horizontal wall between bent up terminal members by means of rolls along symmetry axis. In last but one pass members are bent up by 83-86 deg and in the last pass both horizontal members are additionally bent upwards by 5-8 deg. EFFECT: lowered labor consumption due to enhanced efficiency, reduced idling period and roll wearability. 1 exp, 1 dwg

Description

 The invention relates to rolling production and can be used in the manufacture of unequal corners on profiled multi-mills.

 Bent sections of rolled products (including angular ones) are made by sequentially bending the elements of a strip billet in the calibers of a roll forming mill in several passes. The manufacturing technology of such profiles 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. For the manufacture of bent unequal profiles, an increased number of passes is required (compared with the molding of equal-angled corners) and a more thorough adjustment of the mill, since when profiling them there is a steady tendency to longitudinally twist the profiles towards the small shelf, which also increases the wear of individual forming elements rolls.

 A known method of manufacturing asymmetric bent profiles (unequal corners), in which, in order to reduce their longitudinal twisting, the bending point is reshaped by shifting it towards the large flange of the corner by a certain amount (see ed. St. USSR B 1238825, B 21 D 5/06, 1986). There is also a known method of producing an asymmetric angular profile, in which, in rough passages, part of a larger shelf of a certain length is bent to a height equal to the height of a small shelf in these passages, after which a horizontal section is folded in intermediate passages (see ed. St. USSR N 1625544, B 21 D 5/06, 1991).

 A disadvantage of the known methods is the accelerated wear of individual forming elements of the lower rolls subjected to increased reactive forces from the metal.

 The closest analogue to the claimed object is a method of manufacturing asymmetric bent profiles (see ed. St. USSR N 1315076, B 21 D 5/06, 1987). This method consists in sequentially bending the strip blank elements along the passages and obtaining U-shaped and zigzag profiles, which are then divided into 2 and 3 parts with the help of disk scissors to form corner profiles that are subjected to additional editing in a roller straightening machine. The disadvantage of this method is the need for additional equipment (disc scissors and the correct machine), which increases the labor costs for the production of corner profiles.

 The aim of the invention is to reduce labor costs in the production of bent unequal corners.

To achieve this goal, in the method consisting in sequentially bending the elements of a strip billet with a thickness of 0.7 ... 2.5 mm sequentially and cutting it longitudinally, the horizontal wall is cut between the bent edge elements by rolls along its midline and when these elements in the penultimate pass of the bending angle of 83 ... 86 ^o , and in the last pass both horizontal elements are additionally bent upwards at an angle of 5 ... 8 ^o .

The essence of the technical solution found lies in the longitudinal section of the wall of the formed channel profile (with the shelves inclined to the horizontal at an angle of 83 ... 86 ^o ) in the penultimate caliber of the mill, followed by folding in the last caliber of the received horizontal elements upwards at an angle of 5 ... 8 ^o s the formation of two unequal corners.

 One of the main defects when profiling unequal corners is their longitudinal twisting, due to the inequality of the forces acting from the lower rolls on the shelves of different widths. Since a large force acts on a wider shelf, the corner is twisted towards a narrow shelf. As a result of this, the wear of the roll elements forming the narrow flange of the corner increases, the load on the vertical rollers located between the stands of the mill increases, and its adjustment is difficult. All this leads to an increase in production costs for profiling, i.e. to increase the cost of rental.

 In the proposed method, first, the shaping of the equal-channel channel profile is carried out with the same load on the opposite side elements of the lower rolls, which does not cause any difficulties with calibrating to obtain the desired profile geometry. Then, after longitudinal cutting of the channel wall in the penultimate pass with the help of rolls of a special design (see below), the narrow shelves of the two corners obtained are bent upward in the last pass. Thus, as a result of the application of forces to these shelves, twisting moments are created that are opposite in the direction of the moments from the force from the side elements of the lower roll, which eliminates the longitudinal twisting of unequal corners towards small shelves.

 The proposed method can be implemented in 7-8 passes (depending on the thickness of the workpiece), which is one or two times more than the number of passes with the "same type" profiling of an unequal corner, but an increase in productivity by half when implementing the technical solution found reduces the roll consumption by at least one and a half times.

 The inventive method for the production of bent unequal corners is illustrated in the drawing, which shows two passes (II and V) during the shaping of the equal-channel channel, as well as the penultimate (VII) passage, in which the longitudinal section of the channel is carried out, and the last (VIII), in which the unequal corners.

The strip blank 1 is set in the caliber of the first forming mill stand, where it begins to bend its edge elements 2 to angles α symmetrically to the axial plane of yy calibers; this also forms the wall 3 of the channel intermediate profile. In the penultimate pass, when the edge elements 2 reach a bendable strip of angle α ₇ = 83 ^° ... 86 ^° (the smaller the thickness S of the workpiece, the smaller the value of α ₇ ), the profile wall 3 is cut along the upper and lower rolls of this caliber along with the formation of elements 4 same width "in". In the last pass, the elements 4 are bent upward at an angle β = 5 ^° ... 8 ^° so that α ₇ + β = 91 ^° (some bending of the shelves of the unequal corner is done to compensate for the springing of the bent elements, as a result of which the angle γ between large and small shelves of the finished corner will be close to 90 ^o with a deviation from this value within the tolerance). Large shelves of 5 corners of width B in this passage do not bend, i.e. the reaction force from the side elements of the lower roll is zero, and the longitudinal twisting is very small or absent.

 An experimental verification of the found technical solution was carried out on a continuous bending unit 1 - 4x50 - 300 of JSC Magnitogorsk Iron and Steel Works in the manufacture of unequal corners 40 • 25 • 2 and 50 • 36 • 2.5 mm from Article 3 according to GOST 19772, as well as on the profile bending light type mill 0.3 - 1.5x20 - 90 MMK in the manufacture of corners 25 • 20 • 1.5 mm (GOST 19772) and 20 • 15 • 0.7 mm from st. 08 kp. On the mill "1 - 4" the corners were made in 8 passes, and on the mill "0.3 - 1.5" - in seven.

Rolls of the penultimate stands of both mills were made of increased hardness and stepwise with the height of the “step” (the difference in barrel diameters in its middle): for mill “1 - 4” - 5 mm, for mill “0.3 - 1.5" - 4 mm . In order to prevent the lateral displacement of the cut channels and thereby improve the quality of the cut, the pre-finishing calibers on the mills were performed with the flanges closing the lower rolls. At the mill "1 - 4" unequal corners were obtained from channels, respectively, 50 • 40 • 2 and 72 • 50 • 2, 5 mm (they were formed according to the mode:
0 ^° → 8 ^° → 18 ^° → 30 ^° → 45 ^° → 65 ^° → 80 ^° → 85 ^° ... 86 ^° ),
and on the mill "0.3 - 1.5" - from channels 40 • 25 • 1.5 and 30 • 20 • 0.7 mm (molding according to the mode:
₀ ° _{→ 10} ° _{→ 20} ° _{→ 36} ° _{→ 56} ° _{→ 74} ° _{→ 83} ° _{... 84} °.

In the last stands of the mills, the small regiments of the corners received were bent at an angle of 6 ^o ... 5 ^o (mill "1 - 4") and 8 ^o ... 7 ^o (mill "0.3 - 1.5").

All sizes of finished unequal corners corresponded to permissible values, and longitudinal twisting did not exceed 1 ^o per 1 m of length (norm GOST 19772).

A check was also carried out on the production technology of unequal corners with a longitudinal cutting of the intermediate profile (as per Pat. GDR N 35279), but without additional bending of the horizontal elements of the strip and without editing the corners after the mill. The magnitude of the longitudinal twisting of the finished corners in this case reached 2 ^o per 1 m of length.

 Thus, the experiments confirmed the acceptability of the claimed object to solve the problem and its advantages over the known object.

 According to the central laboratory of MMK, the use of the present invention in the production of bent unequal corners reduces labor costs (by increasing productivity and reducing downtime and roll consumption) by at least 1.8 times, and compared with the known method, taken as the closest analog, about 1.5 times.

An example of a specific implementation. A bent unequal corner 40 • 32 • 2 mm is made in eight passes by longitudinally cutting the walls of the intermediate channel profile 64 • 40 • 2 mm in rolls, formed in seven stands with bending angles α of the edge elements (see Fig. 1)
₀ ° _{→ 8} ° _{→ 18} ° _{→ 30} ° _{→ 45} ° _{→ 65} ° _{→ 80} ° _{→ 85} ° _.
In the last (finishing) pass, the horizontal elements of the cut profile are bent upward at an angle β = 6 ^° with the formation of two unequal corners of the required geometry.

The angle γ = 90 ^° ... 90 ^° 30 ', which meets the requirements of GOST 19772.

Claims (1)

A method for the production of bent unequal corners, comprising sequentially bending the strip billet elements with the formation of an equal-channel channel profile and longitudinal cutting of its horizontal wall along the axis of symmetry, characterized in that in the production of bent non-equal-angle corners from a workpiece with a thickness of 0.7 - 2.5 mm the horizontal wall of the equal-channel channel profile is carried out by rolls when reaching in the penultimate passage the bending angles of 83 - 86 ^o , and in the last pass horizontal the elements of the obtained unequal corners are additionally bent upward at an angle of 5 - 8 ^o .