Method of production of billets at rolling mills

FIELD: process engineering.

SUBSTANCE: proposed method aims at increasing wear resistance of rolls and process efficiency and decreasing wastes at rolling. It comprises making an intermediate blank and its rolling at rolling plant at feed of its front end to rolling unit at initial moment of rolling. Note here that before said feed, this intermediate blank is formed by squeezing its front end at four-hammer press forge to produce conical part with taper angle not larger than friction angle at sections of contact of intermediate blank front end with rolling mill rolls. Note also that reduction of hammers is performed with formation of concave surfaces at front end angles with the help of four hammers appropriately shaped.

EFFECT: perfected rolling process.

4 cl, 8 dwg

 

The invention relates to the field of metal forming, and in particular to methods of obtaining rolled from billets with a pre-deformed bare ends, and can be used in the metallurgical industry for the production of workpieces of different steels, alloys and non-ferrous metals rolling mill.

A known method of manufacturing billets for rolling mills, comprising the manufacture of the intermediate billet and rolling on the blooming mill, in which the deformation of the front end of the billet is produced with relative compression, not less than two times the relative compression of the rear end of the billet (EN 2128094 C1 IPC6WV 1/02, epubl).

There is a method allows to reduce the size of defect type "fishtail" and, accordingly, the amount of leaf trimmings.

The disadvantage of this method is that its implementation requires considerable effort when the compression of the front end of the workpiece. The result is increased wear of the rolls and other parts, increases the load on the engine decreases the performance of the rolling process.

The closest analogue of the proposed method, selected as a prototype, is a method of manufacturing billets for rolling mills, including the production of intermediate pieces, redania the end of the workpiece of a certain shape by compression at the top and bottom crimping tools blooming in the press and subsequent rolling of the rolling installation, including the task of the front end of the billet rolls in the initial rolling (EP 0157575 A2, IPC4B21J 5/00, B21J 13/02, publ. 09.10.1985).

In the known method ingot compresses on the press before rolling to reduce its width and receipt of this form the end of the workpiece, which reduces the value of technological trimmings by reducing defects at the end of the workpiece (for example, very disheveled end and defects such as "fish tail") after rolling.

The disadvantage of this method is that its implementation in the initial rolling, when the task in rolling mill rolls front end of the workpiece occur multiple accents the front end of the billet on the rolls, with the result that he is crimped to the shape required for the capture of rolls. However, rollers and other parts of the mill wear out quickly, increasing the load on the engine, and it takes a long time to ensure capture of the end of the workpiece, which leads to poor performance of the rolling process. In addition, bilateral compression of the billet top and bottom crimping tools blooming in the press leads to lateral broadening of the metal at each compression that does not allow you to get some good quality blank the correct form and substantially reduce the defects at the end of the workpiece, and that the same does not allow to achieve high productivity of the process.

The basis of the invention the task is improving the method of manufacturing billets for rolling mills, in which by changing the operation of the compression on the press is ensured by pre-attaching the front end of the billet with a shape that allows the rolls of the rolling mill is easy to grasp the workpiece without pulling and bumps on it, which leads to increased wear of the rolls, reducing the time of rolling and, as a consequence, the productivity of the process. In addition, by changing the compression scheme achieves a significant reduction of defects at the end of the workpiece, which leads to the reduction of the technological trimmings, but also improves the performance of the process of crimping the ends of the workpiece to the press.

The problem is solved in that in the method of manufacturing billets for rolling mills, comprising the manufacture of the intermediate piece, the compression end on the press and the subsequent rolling of the material in the rolling installation, including the task of the front end of the workpiece at the initial moment rolling in the rolling installation, what is new is that a challenge in rolling mill front end of the workpiece simultaneously compresses four strikers in chetyrehsetovom forging device for press forming a cone with cone angle, n is greater than the angle of friction at the contacts the front end of the billet with the rollers rolling installation, the shape of the working surfaces of these four Boykov allows compressing the corners of the workpiece with the formation of the concave surfaces.

The problem is solved also by the fact that the intermediate billet of rectangular cross-section made by reductions in the slabbing mill, and after compression the front end of the billet in chetyrehsetovom forging device on the press have it rolling on longitudinal camp.

The problem is solved also by the fact that the intermediate workpiece is made hollow, set in its cavity, the mandrel and compression of the front end of the workpiece in chetyrehsetovom forging device perform on the mandrel, and then rolling the obtained billet perform on pillarstone.

The problem is solved also by the fact that before the compression of the workpiece in chetyrehsetovom forging device, its front end is placed on the lower die of the device, and compression is performed by moving the upper striker device vertically downwards, and the two side heads simultaneously toward each other and toward the lower firing.

The problem is solved also by the fact that compression of the billet four strikers in chetyrehsetovom forging device on the press is performed by simultaneous symmetrical movement of the two pairs of strikers in two mutually perpendicular radial the x directions.

The problem is solved also by the fact that compression in chetyrehsetovom forging device carried out on hydraulic forging press.

The problem is solved also by the fact that in the process of forming the conical part of the workpiece carry out more than one compression with Kontokali workpiece after each compression.

Between the set of essential features of the claimed invention and achievable technical result is the following causal link.

Changing the operation of the compression in the press, namely the compression before the task in a rolling mill the front end of the workpiece simultaneously with four strikers in chetyrehsetovom forging device for press forming a cone with cone angle smaller than the angle of friction at the contacts the front end of the billet with the rollers rolling installation, in conjunction with the known characteristics of the claimed invention provides for the formation of the task in a mill of this front end of the billet, which allows rotating the rolls are easy to capture due to the fact that narrowed front end immediately enters into the gap between the rollers, and then rolls rolled billet, with the powers the friction between metal and rolls. While acting on the workpiece pulling force (Roccia on the horizontal axis of the tangential friction force) significantly exceeds the buoyancy force (the projection on a horizontal axis normal reaction rolls), due to the reduction of the required angle of capture in the initial rolling compared to the prototype. Natural grip rollers of the front end of the workpiece is also provided by setting the angle of the taper of not more than the angle of friction, otherwise the pressure force on the workpiece side of the roll exceeds the friction force, and capture difficult. The result is increased wear of the rolls, reduced time rolling and, consequently, increases the efficiency of the process.

In addition, the preliminary compression of the front end of the workpiece simultaneously with four strikers in chetyrehsetovom forging device provides, in addition to the favorable stress-strain state of metal in the deformation zone (especially in the case of maloplastichnye and hard steels and alloys) and the absence of lateral broadening, which leads to quality end of the harvesting high dimensional accuracy, significantly improving the performance of the compression process.

And in the case of compression of the front end of the billet four strikers, the shape of the working surface which allows compressing the corners of the workpiece with the formation of the concave faces, provides further rolling less effort to get the right rectangular in sectional shape of the workpiece due to the fact that the first rolls about imaut upper and lower protruding edge of the workpiece, aligning these surfaces, and thus formed the lateral line broadening side surfaces.

The manufacture of the intermediate hollow billet, the determination in her cavity of the mandrel, the implementation of the compression of the front end of the workpiece in chetyrehsetovom forging device on the mandrel and running then rolling the obtained billet pillarstone provides for compression tight grip mandrel with the workpiece, and further allows the rolling of hollow workpieces with large degrees of deformation (reductions), which ultimately leads to increased productivity of the rolling process, due to the reduced number of passages, and reduce remove waste in the front end of the billet.

The essence of the invention is illustrated by drawings, where figure 1 shows a longitudinal cross-section of the workpiece, the front end of which is crimped strikers chetyrehvalkovoj forging device; figure 2 - cross section A-a in figure 1; figure 3 is a front view of chetyrehvalkovoj forging device with the diluted strikers; figure 4 - schematic capture front end of the billet rolls in the initial rolling; figure 5 - cross section of the crimped end of the workpiece with the concave faces; figure 6 is a longitudinal section of a hollow workpiece, the front end of which is crimped strikers chetyrehvalkovoj forging eliminate the STV; figure 7 - cross section b-B figure 6; Fig - hydraulic press with chetyrehochkovym forging device, while a symmetrical movement of the two pairs of strikers in two mutually perpendicular radial directions.

In the drawings denote: 1 - jaunty chetyrehvalkovoj forging device, 2 - blank 3 - rolling mill rolls, α is the angle of taper of the front end of the billet, 4 - pin, 5 - hydraulic forging press, 6 - chetyrehballnoe forging device 7 to the hydraulic cylinders of the press.

Method of manufacturing billets for rolling mills is as follows.

In-line rolling mill stands before installing the press, for example hydraulic forging press 5, with chetyrehochkovym forging device 6, for example design described in the patent UA 95431 (figure 3).

Made intermediate the workpiece 2, which may be rectangular or round cross-section, and the workpiece may be hollow. Intermediate billet of rectangular cross-section can produce the reductions in the slabbing mill, and a hollow intermediate the workpiece can be produced, for example by stitching sleeves, and then set in its cavity, the mandrel 4 (6, 7).

The front end of the workpiece 2 (and in the case of a hollow workpiece 2 with the mandrel 4 in) simultaneously compresses four strikers 1 in even Rahmonova forging device for press forming a tapered part, with a cone angle α of not more than the angle of friction at the contacts the front end of the billet with the rollers 3 rolling installation. This angle depends on the coefficient of friction between the materials of the workpiece and the rolls and the state of their surfaces, and does not exceed 20° in the case of steel billet and steel rolls at the deformed surface of the workpiece and grinding rolls (1, 2, 6, 7).

After compression of the front tapered end of tube 2 is set at the initial moment rolling in the rolls 3 rolling installation (figure 4). In the place of contact of the narrowed front end of the workpiece 2 with the rollers 3 on the workpiece act normal reaction N of the rolls and the tangent frictional force So due to exceeding magnitude pulling force (projection on the horizontal axis forces T) over the buoyancy force (the projection on the horizontal axis of the reaction N), which act on the workpiece side of the rolls in the initial rolling, rolls easily grasp the workpiece and then rolled it on a rolling installation. This may be a longitudinal mill in the case of a billet of rectangular cross-section or pilkerton in the case of the hollow billet.

This compression of the workpiece in chetyrehsetovom forging device is carried out as follows: the front end of the billet is placed on the lower die of the device, and compression is performed by peremeshany the top striker device vertically downwards, and the two side heads simultaneously toward each other and toward the lower firing (figure 3). We can also perform compression four strikers in chetyrehsetovom forging device on the press by simultaneous symmetrical movement of the two pairs of strikers in two mutually perpendicular radial directions (Fig).

In the process of forming the conical part of the workpiece can implement more than one compression with Kontokali workpiece after each compression.

Compress the front end of the billet of rectangular cross-section can carry out four strikers, the shape of the working surface which allows compressing the corners of the workpiece with the formation of the concave surfaces (figure 5). Further rolling of the rollers compresses the upper and lower protruding edge of the workpiece, aligning the surface, and forming the lateral line broadening side surfaces, obtained the right of rectangular cross section shape of the workpiece.

Example 1 of the method.

Before you start rolling in-line longitudinal rolling mill stands before installed hydraulic forging press force of 25 MN in the workspace which has established chetyrehballnoe forging device with four strikers, equipped with two manipulators (not shown).

The reductions on the slabbing of spotovi and intermediate billet of rectangular cross-section, the front end of the slab (thickness of 220 mm and a width of 900 mm) which was placed on the lower die chetyrehvalkovoj forging device, then perform compression by moving the top striker device vertically downwards, and the two side heads simultaneously toward each other and toward the lower firing. After each compression was carried out by the casting-off of the workpiece using manipulators.

On the front end of the workpiece formed a tapered portion with a taper angle α, equal to 12°. The front tapered end of the workpiece at the initial rolling asked in longitudinal rolls of the mill, who easily captured the workpiece without pulling and bumps on it, and then carried out the rolling. The result is increased wear of the rolls, decreased time rolling, improved process performance and 18-22% decreased technological scraps, compared with the method of the prototype.

Example 2. Before pilgerstra established hydraulic forging press force 5 25 MP with two horizontal cylinders 7, in the workspace which has established chetyrehballnoe forging device 6 with four strikers 1, equipped with two manipulators.

Firmware ingot on piercing mill TPA 6-12" manufactured hollow intermediate the workpiece (the core) with a diameter of 340 mm, the front end of which is using manipu is atora established between the dissolved strikers chetyrehvalkovoj forging device, then using the second manipulator installed in its cavity, the mandrel 4. Performed compression of the front end of the sleeve by moving with the help of hydraulic cylinders 7 simultaneously two pairs of symmetrically Boykov 1 in two mutually perpendicular radial directions. After each compression was carried out by the casting-off sleeves using manipulators.

On the front end of the sleeve is formed a tapered portion with a taper angle α, equal to 15°. The front tapered end of the sleeve in the initial rolling asked in rolls piligrimage mill, who easily captured the workpiece without pulling and bumps on it, and then made rolling on the pipe diameter 219 mm resulted in increased process productivity, and decreased technological scraps on 20-23%.

1. Method of manufacturing billets for rolling plants, including the production of intermediate pieces and its subsequent rolling of the rolling installation with the task of its front end in the initial rolling in the rolling installation, characterized in that before the task in the intermediate rolling mill billet form, compressing its front end at the same time four strikers in chetyrehsetovom forging device for press forming a tapered part with a cone angle smaller than the angle of friction at the contact areas per the last end of the intermediate workpiece with rollers rolling installation, when this compression strikers produced with the formation of the concave surfaces at the corners of the front end of the intermediate pieces through the use of four strikers with the appropriate form of the working surface.

2. The method according to claim 1, characterized in that the intermediate billet of rectangular cross-section is produced by compression in the slab mill with subsequent compression of the front end in chetyrehsetovom forging device on the press.

3. The method according to claim 1, characterized in that the intermediate workpiece is made hollow, set in its cavity Dorn, followed by the compression of its front end by the strikers on the mandrel, and then rolling the obtained billet perform on piligrimages the camp.

4. The method according to one of claims 1 to 4, characterized in that before compression in chetyrehsetovom forging device, the front end of the intermediate pieces are placed on the lower die of the device, and compression is performed by moving the upper striker device vertically downwards, and the two side heads simultaneously toward each other and toward the lower firing.



 

Same patents:

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32 cl

FIELD: metallurgy; methods of rolling of metallic slabs.

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2 dwg

Bar rolling method // 2273534

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1 dwg

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EFFECT: enhanced stability of combination rolling process, high level of mechanical characteristics along the whole length of blank.

2 dwg, 1 tbl

Rolling method // 2284233

FIELD: plastic working of metals, possibly processes for asymmetrical die rolling with use of eccentric rolls.

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EFFECT: enhanced efficiency of method, improved quality of microstructure of ready rolled pieces.

12 dwg

FIELD: ferrous metallurgy; other industries; methods of production of the blooms.

SUBSTANCE: the invention presents the method intended for expansion of the blooms production process capabilities and improvement of the quality of the sectional bars at production out of the steel continuously casting slabs of the blooms used at the rolling of the sectional bars. The method provides for the multi-run drafting of the steel cast product in the rolls with the open box passes and the flat barrel at first into the blooms, and then in the rolls with the open box passes - into the bloom. Improvement of the microstructure of the rolled product and the increased stability of the rolling process is attained due to the fact, that in the capacity of the steel cast product use the continuously cast slab with the ratio of its width to its thickness does not exceed 5.3, which (the slab) is then cogged out into the bloom with the ratio of the thickness to the width of 2.4÷2.6 in the rolls, the average rolling diameter of the passes of which is no less than slab width. At that the drafting of the steel cast slab is conducted with saving of its thickness, and during the first three passes the bloom is swaged with the individual draughts, which are not exceeding the value of 1.15.

EFFECT: the invention ensures expansion of the blooms production process capabilities and improvement of the quality of the sectional bars at production out of the steel continuously casting slabs of the blooms used at the rolling of the sectional bars.

3 cl, 1 tbl

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