RU2094137C1 - Billet manufacture method - Google Patents

Abstract

FIELD: manufacture of rolled products. SUBSTANCE: method involves cutting material into measured lengths and feeding to pressing zone; squeezing end portions in several stages to form strips and wall, with supporting force being applied to strips; rolling billets to obtain ready product. At the first stage, end portion of wall is preliminarily squeezed for value of Δ H determined by expression: Δ H > 2H(s) [B - B(e) + Δ] /B(st), where B is nominal width of billet strip; H(s) is strip thickness; B(e) is width of strip end; B(st) is width of striker; Δ is strip width binding value during wall squeezing. At the second stage, strips with width at least equal to B + Δ are formed. EFFECT: increased efficiency and improved quality of product. 4 dwg

Description

 The invention relates to the processing of metals by pressure and can be used in the manufacture of blanks for rolling shaped sections.

 There is a known method of forming blanks [1] comprising pre-crimping their ends with a press bar to create external "hard" zones that reduce the amount of rolling at the front and rear ends. Nevertheless, the loss of metal by trimming is quite large, since in the process of crimping the ends a roll is already formed, which cannot be eliminated during subsequent rolling.

 As a prototype, a method for producing blanks [2] of a predominantly shaped profile was adopted, which includes cutting the roll into measuring blanks, feeding it to the press zone, compressing the end sections in several stages with the formation of shelves and walls, with the application of supporting forces to the shelves and subsequent rolling to the finished product .

 The method allows to increase the yield and improve the quality of the products. The disadvantages of this method include the loss of metal for trimming, due to non-fulfillment of the profile of the flanges at the end sections due to a shortage of metal in the shelves.

 The objective of the invention is to reduce the default profile at the ends of the finished roll.

где B номинальная ширина полки заготовки,
H_n толщина полки,
B_б ширина бойка,
B_k толщина полки на торце,
Δ величина утяжки по ширине при обжатии стенки,
а на втором формируют полки шириной не менее B+D.The problem is solved by pre-filling the shelves of the metal billet and is achieved by the fact that in the known method for producing billets of predominantly shaped profile, which includes cutting the roll into measuring billets, feeding it into the press zone, compressing the end sections in several stages with the formation of shelves and walls, with the application of back-up forces to the shelves and subsequent rolling to the finished product, according to the invention, at the first stage, preliminary compression of the wall of the end sections by ΔH, determined from the expression

where B is the nominal width of the workpiece shelf,
H _n shelf thickness
B _{b the} width of the striker,
B _{k the} thickness of the flange at the end,
Δ is the width in the case of compression of the wall,
and on the second form shelves with a width of at least B + D.

 In FIG. 1 shows the initial position of the workpiece, strikers and a longitudinal section; in FIG. 2 preliminary compression of the wall of the end section and a longitudinal section; in FIG. 3 the formation at the end of the shelves with a width of B + D and a longitudinal section; in FIG. 4 final compression of the end of the wall with lateral support of the shelves and a longitudinal section.

 The method is implemented as follows.

 The workpiece 1 is fed to the lower press head 2 of the press and clamped from above by the upper striker 3; horizontal strikers 4 at the same time divorced. In the course of the lower striker, preliminary compression of the wall of the end section is carried out by the amount DH, derived from the following considerations. In order to eliminate the deficit of metal in the flange elements (shelves) of the profile and compensate for the tightening of the shelves in width when compressing the wall, it is necessary to displace the metal from the wall from under the strikers and redistribute it between the flanges.

The volume of metal displaced from under the strikers for conditions of plane deformation is
ΔH • B _b ,
where ΔH is the absolute compression value,
B _{b the} width of the striker.

Given the magnitude of the drawdown Δ of the shelf in width when compressing the wall, the metal deficiency in the flange elements is
2H _p (BB _k + Δ),
where H _{n the} thickness of the shelf (average);
B is the nominal width of the workpiece shelf (in its middle part);
B _{k the} width of the shelf at the end.

Процесс пластического формоизменения сопровождается образованием переходного участка 5 от обжатой зоны к необжатой и небольшого языка 6 по стенке, а также отходом консольных частей 7 от боковых граней бойков 2 и 3 (фиг. 2).Thus, a variable condition for eliminating the deficit of metal in the shelves at the end sections is the following condition
ΔH • B _b > 2H _p (BB _to + Δ),

The process of plastic forming is accompanied by the formation of a transition section 5 from the compressed zone to the uncompressed and small tongue 6 along the wall, as well as the departure of the cantilever parts 7 from the side faces of the strikers 2 and 3 (Fig. 2).

 The horizontal strikers 4 compress the cantilever parts 7 until the shelves 8 are formed at the end of the workpiece with a width of at least B + Δ where B is the nominal width of the shelf in the stationary part of the workpiece, D is the width of the shelf during the compression of the wall (Fig. 3). Next, the horizontal strikers 4 are diverted from the shelves 8 and installed at a distance between their working surfaces equal to the nominal width of the workpiece in the stationary part to create lateral support. Vertical strikers 2 and 3 produce the final formation of the wall 9 at the end of the workpiece (Fig. 4). The process is accompanied by free broadening of the metal, with the shelves 8 moving away from the strikers 2 and 3 until they come into contact with the horizontal strikers 4, as a result of which the width of the workpiece at the end becomes the same as in the stationary part. The thinning of the wall 9 is accompanied by a corresponding tightening of the shelves by a value of D, therefore, at the end of the deformation process, the width of the shelves at the ends will be equal to the width of the shelves in the stationary part. Due to repeated compression along the wall, the strikers 2 and 3 are released from the compressive action from the shelves. A blank with a formed front end is fed through the working space of the press and the rear end is similarly crimped. A fully formed workpiece is fed to the rolling mill.

Исходя из этого величину абсолютного обжатия ΔH принимают равной 55 мм. За счет вытеснения металла из под бойков образуется язык по стенке длиной 20 мм. Процесс обжатия сопровождается также отходом необжимаемой части заготовки от бойков с образованием переходного участка. Ходом горизонтальных бойков обжимают консольные части до формирования полок на конце шириной 370 мм, что на 20 мм превышает ширину заготовки в средней (стационарной части). Горизонтальные бойки отводят от полок на концевом участке и устанавливают на расстоянии, равном номинальному размеру по ширине заготовки (530 мм). Рабочим ходом нижнего бойка окончательно формируют стенку толщиной 40 мм; при этом величина абсолютного обжатия составляет 35 мм. В результате этого обжатия вертикальные бойки освобождаются от сжимающего воздействия со стороны полок, а ширина заготовок на обжимаемом участке становится одинаковой с необжимаемой остальной частью заготовки, при этом величина языка по стенке увеличивается на 10 мм. Расчетное усилие в конце процесса деформации стенки составляет 650 тс, полок 450 тс. Заготовку с полностью сформированным передним концом подают через рабочее пространство пресса и аналогичным образом обжимают задний конец, после чего ее направляют с помощью транспортных рольгангов к обжимной клетки для прокатки в реверсивном режиме.Example. It is required to obtain a shaped blank with crimped ends for rolling a normal I-beam 55B1 according to GOST 26020-83. Steel grade St.3sp. The shaped section formed on blooming is preliminarily cut into measuring blanks 4.5 m long. The I-shaped blank has the following nominal dimensions: wall thickness 130 mm, wall width 370 mm, shelf thickness 85 mm, shelf width 350 mm, total width (height) 530 mm At the front and rear ends of the workpiece, the profile is distorted and has the following dimensions: profile width on the side of the burr 576 mm, wall width on the side of the burr (distance between the inner faces of the shelves) 340 mm, the width of the shelves on the end due to metal tightening 280 mm. To form the ends of the shaped workpieces, a double-acting hydraulic press is used with 320 mm vertical strikers for wall compression and flat horizontal strikers for lateral compression on the shelf side. An I-shaped billet heated to a temperature of 1200 ^° C is fed into the working space of the press and installed on the lower movable hammer, while the initial length of the crimped section is 150 mm. With a working stroke of the lower striker, preliminary compression of the wall of the end section is performed by the amount DH determined from the expression

Based on this, the absolute compression ΔH is taken equal to 55 mm. Due to the displacement of metal from under the strikers, a tongue is formed along a wall 20 mm long. The crimping process is also accompanied by the departure of the incompressible part of the workpiece from the strikers with the formation of the transition section. In the course of horizontal strikers, the cantilever parts are crimped to form shelves at the end with a width of 370 mm, which is 20 mm greater than the width of the workpiece in the middle (stationary part). Horizontal strikers are diverted from the shelves at the end section and installed at a distance equal to the nominal size over the width of the workpiece (530 mm). With a stroke of the lower striker, a wall 40 mm thick is finally formed; wherein the absolute compression ratio is 35 mm. As a result of this reduction, the vertical dies are freed from the compressive action from the shelves, and the width of the workpieces in the squeezed section becomes the same with the incompressible rest of the workpiece, while the size of the tongue along the wall increases by 10 mm. The estimated force at the end of the wall deformation process is 650 tf, shelves 450 tf. A blank with a fully formed front end is fed through the working space of the press and the rear end is crimped in the same way, after which it is sent using transport conveyors to the crimp cage for rolling in the reverse mode.

Claims (1)

A method of obtaining preforms of predominantly shaped profile, including cutting the rolled into measured billets, feeding to the press zone, compressing the end sections of the workpiece in several stages with the formation of shelves and walls, with the application of efforts to support the shelves and subsequent rolling to the finished product, characterized in that the first stage produce preliminary compression of the wall of the end sections by the value ΔH, determined from the ratio

where B is the nominal width of the workpiece shelf;
N _{p the} thickness of the shelf;
In _{to the} width of the shelf at the end;
In _{b the} width of the striker;
Δ is the magnitude of the drawdown of the shelf in width when compressing the wall,
and at the second stage, form shelves with a width of at least B + Δ.z

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