RU2103088C1 - Method of making bent box shapes - Google Patents

Abstract

FIELD: plastic metal working, namely manufacture of bent box shapes. SUBSTANCE: method comprises steps of successive bending up closing flanges and lateral flanges of shapes in rough, intermediate and finish passes and partially unbending lateral flanges in finishing pass up to 90 degrees; providing 15 degree increment of bending angles of closing flanges at making shape of strip blank with thickness 5 - 8 mm in rough passes and disengaging tool and strip in two intermediate passes; unbending closing flanges by 0.5 degree when angle between said closing and lateral flanges achieves 70-72 degrees; providing maximum bending angle of lateral flanges equal to 20 degrees, rebending said flanges by 2- 3 degrees in first finishing pass according to manufacturing process and unbending them beginning from second finishing pass. EFFECT: enhanced efficiency. 1 dwg

Description

 The invention relates to rolling production and can be used in the manufacture of cold-formed closed (box-shaped) profiles on roll forming multi-stand mills.

 Bent sections of rolled products (including closed ones) are made by successively bending the elements of a strip billet in the calibers of a profile bending mill for several rough, intermediate and finishing passes [1]. For the production of box-shaped profiles according to well-known technological schemes, depending on their size, 10-14 passes (2-4 rough, 6-7 intermediate and 2-3 finishing) are required, and the continuous profiling process requires fewer passes in comparison with semi-continuous and single processes .

 A known method of manufacturing bent box-shaped profiles, in which technological flanging is performed at the first transitions on the workpiece, then the shelves and walls are bent with free flexible flange followed by lateral compression of the shelves and removal of technological flanges, which ensures the size of the “gap” between the edges of the joined shelves [2] .

 The disadvantage of this method is the inability to use the same set of rolls for the manufacture of box-shaped profiles from blanks of various thicknesses (for example, 5-8 mm), which increases production costs, and then gives additional metal consumption for flanging.

The closest analogue to the claimed object is the production technology (calibration) of a closed square profile of 100x100x5 mm [3], which includes sequential folding of the connecting and side shelves of the profile in draft, intermediate and finishing passes and is characterized by the fact that the maximum increment of the folding angles of the connecting shelves of the profile is equal 20 ^o , and the side 10 ^o , unbending the last of them only in the finishing passage at an angle equal to 1 ^o .

 The disadvantage of the described technology for the production of bent box-shaped profiles is also the difficulty of using this set of rolls for profiling workpieces of different thicknesses, as well as an excessive number of passes, which increases production costs by increasing the consumption of rolls.

 The aim of the invention is to reduce the consumption of roll forming rolls and thereby production costs by optimizing some profiling parameters.

To solve this problem, in a method that includes sequential folding of closing and side flanges of a profile in rough, intermediate and finishing passages and partial bending of side flanges in a finishing passage to an angle of 90 ^o , when forming a strip blank 5-8 mm thick, the increment of the angle of folding of the connecting shelves in roughing passes is made to be 15 ^o with their release from contact with the instrument in two intermediate passes, and upon reaching the angle between 70-72 ^o interlock and lateral flanges carried razgibku first of them at an angle of 0.5 ^o, m and ksimalnoe increment angles hems of the lateral flanges is made to be 20 ^o, wherein peregibku produce them at 2-3 ^o Predchistovaya in the first pass, followed razgibkoy, beginning with the second passage Predchistovaya.

 The essence of the technical solution is to optimize the values of the maximum increments of the bending angles (this is the difference between the bending angles in the subsequent and previous adjacent passages) of the closing and side shelves, in the partial unbending of the closing shelves, in increasing the bending angle and, accordingly, the partial unbending of the side shelves of the profile in the finishing passes . As a result of this, it becomes possible to use the same set of work rolls for profiling workpieces of different thicknesses.

 It is known that one of the basic requirements for the geometry of a bent box-shaped profile is the constancy of the width of the gap between the interlocking shelves, which causes difficulties when using passages with free flexible and, in particular, in the absence of contact of the interlocking shelves with the upper and lower rolls. Therefore, the known methods of manufacturing bent box-shaped profiles practically exclude the possibility of forming on one set of rolls and even blanks with a thickness difference of 1.5-2.0 mm.

 The drawing shows a diagram of a method providing the possibility of obtaining high-quality box-shaped profiles of the same sizes B and H, but with a thickness difference of 3 mm.

= 469,9 мм (при R = 8 и δ = 3 мм);
для S = 5 мм -

= 491,3 мм (при R = 5 и δ = 3 мм).If, for example, a box-shaped profile is formed with B = 145 mm and H = 120 mm, but with a thickness of S = 8 mm and S = 5 mm, a blank of different widths will be required, determined from the expression:
B _s = 2H + 2B-8 (R + S) + 2π (R + k • S) -δ,
where R is the inner radius of the bend of the finished profile, mm;
k is a coefficient depending on the value of R / S;
δ is the gap clearance of the shelves,
those. for our example, with R / S = 1 and K = 0.41:
for S = 8 mm -

= 469.9 mm (with R = 8 and δ = 3 mm);
for S = 5 mm -

= 491.3 mm (at R = 5 and δ = 3 mm).

мм компенсируется выполнением профиля толщиной 8 мм с размерами B и H в плюсовом поле допуска, а профиля с S = 5 мм - в минусовом поле допуска. Очевидно, что профиль с S = 5 мм будет с B и H, близкими к номинальным размерам.Difference in workpiece width

mm is compensated by making a profile with a thickness of 8 mm with dimensions B and H in the positive tolerance field, and a profile with S = 5 mm in the negative tolerance field. Obviously, a profile with S = 5 mm will be with B and H close to the nominal dimensions.

The stabilization of δ in the proposed method for all possible thicknesses is achieved, firstly, by reducing the increment of the bending angle of the closing shelves of the profile in rough passages, and secondly, by the absence of this increment in 4 passes (from V to VIII - see drawing ) and, thirdly, by partial unbending (by 0.5 ^o ) of these shelves in the XI passage (which reduces the "springing" of these elements).

The decrease in the number of passes is achieved by increasing the increment of the angle of folding of the side shelves in the intermediate passages (V to X) to 20 ^o and the large amount of inflection of these shelves (2-3 ^o ) in subsequent passes.

 The drawing shows the most characteristic passages: III, VI, VIII, X, XI, XII and XIII. Passages I-IV are rough, V-X are intermediate, XI-XIII are fair.

In finishing passages I-IV, only the closing shelves of I are bent, and the increment of the bending angles in each of these passages is 15 ^o (i.e., α ₄ = 60 ^o ). Starting from the V (1st intermediate) passage, the shelves 2 are bent at angles β with a maximum increment of these angles equal to 20 ^o ; at the same time, in the VII and VIII passes, the closing shelves 1 are released from contact with both the upper roll 3 and the lower 4, and the upper roll is in contact with the profile wall 5 and the lower part of the side shelves 2.

The bending of the closing shelves 1 is resumed in the IX passage due to their contact with the forming protrusions 6 of the upper roll. When the angle α = 70-72 ^o is reached between the adjoining and side shelves, the first of them are unbent at an angle of 0.5 ^o (in our case, this occurs in the first preflight - XI pass) with subsequent folding of the shelving (in XII and XIII passes ) to a value of α = 91 ^o , which is necessary to compensate for their spring up.

In the first pre-finishing passage, the side shelves are bent inward (to the yy axis of profiling) by 2-3 ^o (up to β = 92-93 ^o ), and in the second pre-finishing (XII) and finishing (XIII) passes, these shelves are bent to an angle β = 90 ^o . The finishing gauge is formed only by the upper 3 and lower 4 rolls, which facilitates its adjustment.

An experimental verification of the technical solution found was carried out on a roll-forming semi-continuous mill 2-8 x 100-600 of Magnitogorsk Iron and Steel Works JSC in the manufacture of bent box-shaped profiles 145 x 120 and 240 x 85 mm with a thickness of 5-8 mm from steel with σ _in ≤ 47 kgf / mm ² . Two systems of calibers were tested: the known one, chosen as the closest analogue, and the proposed one, made according to the claimed method.

 In both cases, the gauge elements were calculated based on the conditional workpiece thickness S = 6.5 mm (average value between 5 and 8 mm). At the same time, according to the known method, profiling was carried out in 14 passes, and according to the proposed method, for 13 passes.

 According to the claimed method, profiles were obtained with a nominal thickness of 5-8 mm from a workpiece with a thickness of 4.8 to 8.25 mm, fully meeting the requirements of the technical conditions, manufactured in the same calibers, using the known method, it was possible to obtain high-quality box-shaped profiles only from a workpiece with a thickness of 5.8 mm (nominal thickness 6.0 mm, but in the negative tolerance field) and 7.2 mm (rolling the workpiece in a positive field). A further decrease or increase in the thickness of the workpiece led to the sorting of up to 43% of the profiles due to the mismatch of their geometry with the requirements of technical specifications.

 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 manufacture of bent box-shaped profiles will reduce production costs by 20-30% by using the same rolls when profiling a workpiece with a thickness of 5-8 mm and reducing the number of passes.

 Example. The bent box-shaped profile 145x120x5-8 mm is made in 13 passes with the following main parameters of profiling.

The bending angles of the closing (α) and side (β) shelves of the profile along the aisles: I -α ₁ = 15 ^o ; II - α ₂ = 30 ^o ; III - α ₃ = 60 ^o ; IV-α ₄ = 60 ^° ; V - α ₅ = 60 ^o ; β ₅ = 20 ^o ; VI - α ₆ = 60 ^o ; β ₆ = 35 ^o ; VII - α ₇ = 60 ^o (without contact of the shelving with the tool); β ₇ = 50 ^o ; VIII - α ₈ = 60 ^o (similar to the VII passage); β ₈ = 65 ^o ; IX - α ₉ = 65 ^o ; β ₉ = 75 ^o ; X - α ₁₀ = 70 ^o ; β ₁₀ = 85 ^o ; XI - α ₁₁ = 69.5 ^o (partial extension of the closing shelves); β ₁₁ = 92.5 ^o (inflection of the side shelves into the profile); XII - α ₁₂ = 84 ^o ; β ₁₂ = 91 ^o (partial extension of the side shelves); XIII - α ₁₃ = 91 ^o ; β ₁₃ = 90 ^o - finished profile.

Claims (1)

A method of manufacturing bent box-shaped profiles, comprising sequentially bending the closing and side shelves of the profile in draft, intermediate and finishing passes and partial unbending of the side shelves in the finishing passage to an angle of 90 ^° , characterized in that when forming the profile from a strip blank 5-8 mm thick, the angle increment the folds of the closing shelves in the rough passages are made equal to 15 ^o with their release from contact with the tool in two intermediate passages, and upon reaching an angle of 70 - 72 ^o between the closing and side shelves of the wasp bend the first of them at an angle of 0.5 ^o , and the maximum increment of the bending angles of the side shelves is equal to 20 ^o , while in the first finishing process, they are bent by 2 3 ^o followed by unbending, starting from the second finishing pass .