EP1085949B1 - Method for producing metal shapes with a polygonal cross-section by means of continuous casting on a double-flanged wheel and continuous rolling - Google Patents

Abstract

The invention relates to a method for producing metal shapes with a partially or totally polygonal cross-section by means of continuous casting in a double-flanged wheel and continuous rolling using a series of at least 3 pairs of rollers with a peripheral flange, whereby said rollers are alternately horizontally and vertically disposed in a symmetrical position with respect to said shape. The inventive method is characterised in that the flanges of the first pairs of rollers are identical to those used to produce shapes with a circular cross-section; the last pair of rollers has flanges defining a section that corresponds substantially to that of the desired shape; the section formed by the grooves of the last pair of rollers has curve radiuses of between 1 and 5 mm at the highest points of the polygon; the sides of the polygon that are not parallel to the air gap pertaining to the last pair of rollers have a clearance angle of ½-3° in comparison with the corresponding of the section of the final shape. The invention can be used to produce copper or aluminum alloy shapes for drawing or and/or subsequent redrawing.

Description

Field of the invention

The invention relates to a method for manufacturing metal profiles, in particular of aluminum alloys, continuously rolled by a series of pairs of rollers from a blank obtained by continuous casting in a grooved wheel, possibly followed by one or more stages of drawing or drawing and annealing.

State of the art

We have been manufacturing wire rod for many years in non-ferrous alloys, in particular in aluminum alloys, from a blank cast continuously in the groove of a wheel that is rotated, the groove being closed by a driven ribbon by the wheel. We know 2-wheel casting systems with a small support wheel, 3-wheel systems, such as the Properzi casting described in GB patent 1143264, 4-wheel systems such as the Pechiney 4R casting described in FR 1178580, and 5-wheel systems like that described in US 3416596.

The blank, generally of triangular or trapezoidal section, is then laminated. continuously through a series of successive cages formed of two rollers, and alternately horizontal and vertical, to obtain a wire of circular section, which can be used as is or processed by wire drawing.

In the case of aluminum alloys, the process is widely used for alloys lightly charged, intended in particular for electrical conductors. With some adaptations, described for example in patents FR 2234936 (Secim and Aluminum Pechiney), FR 2304414 (Secim) and FR 2359613 (Aluminum Pechiney), it was possible to sink and laminate avoiding causing porosities of alloys more loaded at higher solidification intervals, such as alloys in the 2000 series, 5000 and 7000 according to the designations of the Aluminum Association, usable for mechanical applications.

To the knowledge of the applicant, none of the casting-rolling machines Continuous Continents has never manufactured non-circular section products. Certainly there It is normal to use round rod when the final drawn product is itself round wire, which is the case for example for electrical conductors or wire for toasting. On the other hand, there are, in particular in mechanical applications, drawn products of non-circular cross-section, for example rectangular, triangular, polygonal or tee-shaped, for which it would be more economical to start from a wire neighboring machine, which would limit wire drawing passes, or even get out of the casting-rolling machine with final dimensions without subsequent drawing.

One of the reasons that could explain the absence on the section of wire rod section non-circular is due to the difficulty of controlling the geometry of the rolling profile. For a circular section indeed, the product leaving the last rolling stand does not rests on the groove of the rollers only by a generator, and its detachment at the outlet does no problem. It is not the same for products whose section has a flat part, for example a rectangular, triangular or tee shape. They rest on the throat of the rollers of the last cage by a strip more or less wide, whose irregular detachment causes distortions in the geometry of the rolled product, as well as surface defects.

Subject of the invention

The object of the invention is to remedy this drawback and to allow control precise geometry of the section of the rolled product, when this section includes a polygonal part, that is to say at least two intersecting straight parts. The profile laminate can then be used directly as it is, or drawn or drawn to obtain a non-circular section wire, with a smaller number of passes than from a circular section.

• les gorges des premières paires de galets sont identiques à celles des galets utilisés pour la fabrication de profilés de section circulaire,
• la dernière paire de galets comporte des gorges délimitant une section correspondant sensiblement à celle du profilé désiré,
• la section formée par les gorges de la dernière paire de galets présente aux sommets du polygone des rayons de courbure compris entre 1 et 5 mm,
• les côtés du polygone non parallèles à l'entrefer de la dernière paire de galets présentent, par rapport aux côtés correspondants de la section du profilé final une dépouille comprise entre ½ et 3°.

The subject of the invention is a method of manufacturing metal profiles of partially or totally polygonal section by continuous casting in a grooved wheel and continuous rolling using a series of at least 3 and preferably from 3 to 8 pairs of rollers provided with a peripheral groove, these rollers being arranged symmetrically with respect to the profile, and alternately horizontal and vertical, a process which is characterized in that:

• the grooves of the first pairs of rollers are identical to those of the rollers used for the manufacture of profiles of circular section,
• the last pair of rollers has grooves defining a section corresponding substantially to that of the desired profile,
• the section formed by the grooves of the last pair of rollers has radii of curvature between 1 and 5 mm at the vertices of the polygon,
• the sides of the polygon which are not parallel to the air gap of the last pair of rollers have, in relation to the corresponding sides of the section of the final profile, a clearance between ½ and 3 °.

The invention also relates to a method for manufacturing metal profiles drawn or drawn partially or fully polygonal in section from blanks of partially or totally polygonal cross-section obtained by continuous casting in a grooving and continuous rolling wheel, in which the number of drawing passes or wire drawing and the number of anneals are each reduced by at least a third compared to to the process of the prior art starting from a roughly substantially circular section blank.

Description of the figures

FIG. 1 represents a continuous casting machine on a grooved wheel and the train continuous rolling of the blank.

Figures 2 to 5 show, in section through the plane of their axes of rotation, the last pair of rollers used for rolling the profiles described in the examples 1 to 4.

Description of the invention

The manufacturing method according to the invention uses a casting machine comprising a liquid metal feed nozzle (1), a casting wheel (2), which is rotated, provided with a peripheral groove, closed by a metal strip (3) driven by the wheel. The machine can be a two-wheel machine and a caster like that shown in FIG. 1, the second wheel (4) being used for tensioning the ribbon, and the caster (5) being intended to hold the ribbon on the casting wheel. in the vicinity of the casting area. The machine can also be a machine with three, four or five wheels. The section of the blank (6), generally trapezoidal, varies according to the installations between 900 and more than 3000 mm ² .

The number of rolling stands (7), each comprising a pair of rollers, is greater than two and preferably between 3 and 8. This number depends on the final section to be obtained, since the starting section is linked to the casting machine and therefore cannot be changed easily. The reduction in section at each cage is, in general, between 10 and 40%. The accuracy of the geometry improves with the number of cages, but conversely a high number of cages tends to harden the metal, making subsequent wire drawing more difficult. The first cages use rollers with the same grooves as those used for the rolling of the section wire circular. The penultimate cage may include, as the case may be, identical rollers on the former, either flat pebbles or pebbles similar in shape to the pebbles of the last cage, which in all cases have grooves delimiting a section corresponding to the desired final section.

However, experience has shown that if this section is too close to the section final, we cannot respect acceptable dimensional tolerances. Of even, experience has shown that if the radii of curvature between the planar faces are too small, the metal tends to stick to the rollers, which causes incidents on the line and forces stops. According to the invention, these drawbacks are avoided by a adaptation of the shape of the groove of the finishing rollers, which ensures easy removal and good filling of the shapes of the grooves. This adaptation is obtained by providing radii of curvature between the flat faces between 1 and 5 mm, and, for faces not parallel to the air-gap of the rollers, the undercuts, that is to say the angles between the groove and the corresponding face of the profile, between ½ and 3 °.

Special precautions must be taken when winding the profile at the end of rolling. Contrary to the winding of the wire with circular section, it is necessary to envisage a small space between the turns and prevent them from overlapping.

The continuous casting process according to the invention makes it possible to produce profiles metallic; in particular of aluminum or copper alloys, of square section, rectangular, triangular, and more generally partially or totally polygonal, with good dimensional tolerances, of the order of 0.1 mm, and with good detachment of the metal from the last rolling stand.

These profiles can be used as is in many applications mechanical or electrical, or for the manufacture of welding wire. They can also be processed by drawing or drawing in one or more passes, in order to confer dimensions, tolerances on dimensions and shape, or characteristics special mechanics. Some of these products, obtained from wire rod circular section, are known. Using as a draft for wire drawing or drawing a wire rod with a partially or totally polygonal cross section depending on the invention considerably simplifies the manufacturing process since the shape of the cross section of the blank can be very close to that of the drawn product wish. In addition, lubricant leaks between the metal and the die are avoided. obtains when the geometries of the blank and the die are too different. The process for manufacturing partially or totally drawn or drawn wire of section polygonal according to the invention is characterized in that one chooses, for a section data of the final profile, a rough section such as the number of drawing passes or wire drawing and annealing can be minimized. Compared to a section wire rod substantially circular, and choosing for each drawing or drawing pass, a work hardening rate E = (inlet section - outlet section) / outlet section close to the maximum value (around 80% for aluminum alloys) that can support the wire without developing unacceptable defects, the skilled person may define, for an aluminum alloy or copper wire, a range of manufacturing such as the number of drawing or drawing passes and the number of annealed are each reduced by at least a third. This gain is greater for sections which, at least locally, deviate the most from a circular section (sections in V or in T, very elongated flats and in particular those having a section such as the width to thickness ratio is greater than 2).

The exact number of drawing or drawing passes depends on the type of alloy used, as well as parameters of the drawing or drawing process. For alloys aluminum and square or triangular section profiles, we can most often limit stretching or drawing to a single pass with annealing, instead of at least two passes and two anneals starting from a circular blank. For profiles of rectangular section with a width to thickness ratio between 1 and 2, we may limit drawing or drawing to two passes and one annealing, and for reports width on thickness between 2 and 5, three passes and two anneals. The profiles of rectangular section with a width to thickness ratio greater than 4 are moreover, very difficult to draw by drawing from a section blank round, so that the method according to the invention allows a widening of the possibilities of manufacturing wire drawing.

The process according to the invention can be used for a wide variety of alloys of metal, especially aluminum alloys, including treatment alloys thermal (2000, 6000 and 7000 series), and copper alloys.

Examples

For all the examples, the metal was cast on a continuous casting machine of the 3-wheel type, in a grooved wheel leading to a trapezoidal shape blank, of greater width 41 mm and height 29 mm, ie a rough section of 1050 mm ² .

Example 1

From a section blank 1050 mm ² , made of aluminum alloy 5754 according to the designation of the Aluminum Association, a section of square section 13 x 13 mm is produced, by rolling through 6 cages, each comprising a pair of circular shaped rollers in Z38CDV5 steel treated at 52 HRC. At the exit from each cage, the speeds mentioned in table 1 are obtained, as well as the sections in the formats indicated in the same table: Cage No. rollers section format (mm x mm) speed (m / s) 1 Standard 45 x 19.5 19 2 Standard 27 x 26 29.5 3 Standard 33 x 13.9 38 4 Standard 17.5 x 18 57 5 Plate spacing 12.5 83 6 Square 13.2 x 13.2 84

The first 4 pairs of rollers have grooves defining a circular section, as is the case for continuous rolling of circular shaped profiles. The fifth pair of rollers defines a flat air gap and the sixth defines a section square very close to that of the finished product. The air gap between the pebbles of this sixth pair is 2 mm. The radii of curvature of the section of the grooves of the rollers at the 4 vertices of the square are 3 mm. The remains on the sides of the square perpendicular at the air gap of the rollers are 1 °.

No bonding of the profile is obtained on the output rollers and the tolerances on the section of the profile are less than 0.1 mm.

Example 2

From a blank of the same section as in the previous example, a flat 16.5 x 8.1 mm rectangular section in 2017 aluminum alloy is produced by continuous rolling through 6 cages. The types of rollers used, the formats and the speeds at the exit of each cage are mentioned in Table 2. cage n ° rollers section format (mm x mm) speed (m / s) 1 standard 45 x 19.5 19 2 standard 27 x 26 29.5 3 standard 33 x 13.9 38 4 standard 17.5 x 18 57 5 standard 21.6 x 10.2 83 6 rectangular 16.5 x 8.1 114

The first 5 pairs of rollers have standard grooves similar to those used for rolling circular section profiles. The sixth pair presents a 1.5 mm air gap and its grooves delimit a rectangle whose vertices have a radius of curvature of 2 mm and the sides perpendicular to the air gap a draft 1 °. No bonding of the profile is observed at the exit of the last cage and the tolerances on the dimensions of the profile are less than 0.1 mm.

Example 3

An aluminum alloy 1370 profile is produced having a cross section in the general shape of a circular sector, delimited by a triangle at the bottom and an arc of a circle at the top, forming part of a rectangle 16.2 x 12.2 mm, and 150 mm section ² . The types of rollers, formats and speeds at the exit of each cage are indicated in Table 3 cage n ° rollers section format (mm x mm) speed (m / s) 1 standard 45 x 19.5 19.6 2 standard 27 x 26 30.1 3 standard 33 x 14.6 41.2 4 standard 18 x 18 64.2 5 sector 17.3 x 14.8 88.2 6 sector 12.2 x 16.2 114

The first 4 pairs of rollers have standard grooves similar to those of the rollers used for continuous rolling of circular section profiles. The gorges of the fifth pair delimits a sector-shaped section The sixth pair has grooves delimiting a section in the shape of a circular sector, with a radius of 3 mm curvature between the 2 flat parts, a draft of 1 ° on these flat parts and an air gap between the 2 rollers of 1.5 mm. The upper part of the section, in the shape of an arc is carefully polished. No bonding of the profile is observed at the exit of the last cage and the tolerances on the dimensions of the profile are less than 0.1 mm.

Example 4

A profile is produced, intended for electrical applications, of aluminum alloy 1370 of the form shown in FIG. 4 of section 490 mm ² . The types of rollers, formats and speeds at the exit of each cage are shown in Table 4: Cage No. rollers section format (mm x mm) speed (m / s) 1 Standard 45 x 20.5 18 2 Dish 28 x 19.5 28 3 of form 32

Only 3 cages are used, only the first of which has standard rollers. The second cage has flat rollers and the third has rollers whose grooves delimit the section desired. For this last pair, the radii of curvature at the vertices of the sharp angles are 1.1 mm and the draft on the vertical faces 1.5 °. The gorges are very carefully polished. The air gap used is 2 mm.

Example 5

We realize a square wire of square section 10 x 10 mm in aluminum alloy 5754, intended for the manufacture of studs for the fixing of bakelite handles on aluminum cooking utensils, by drawing in a single pass from the profile 13 x 13 mm square section described in Example 1. The usual range according to art anterior started from a circular section blank with a diameter of 18 mm and included two wire drawing passes, separated by an annealing-greasing in 13 x 13 mm format.

Example 6

We made a flat wire of section 15.0 x 4.0 mm in aluminum alloy 2017 from a flat profile of rectangular section 16.5 x 8.1 mm described in Example 2, by wire drawing in one three wire drawing passes, separated by annealing-greasing with intermediate formats 16.0 x 6.3 mm and 15.65 x 4.45 mm. The usual range according to the prior art started from a circular section blank with a diameter of 18 mm, and consisted of 6 drawing passes separated each time by a grease annealing intermediate formats: 17.3 x 13.8 mm, 16.6 x 10.7 mm, 16.2 x 8.2 mm, 16.0 x 16.3 mm, 15.65 x 4.85 mm.

Claims (15)

1. A process for manufacturing metal sections of partially or totally polygonal cross-section by continuous casting in a grooved wheel and continuous rolling by means of at least 3 and preferably from 3 to 8 pairs of rollers fitted with a peripheral groove, these rollers being placed symmetrically relative to the section, and alternately horizontal and vertical, characterised in that:

   the grooves of the first pairs of rollers are identical to those of the rollers used for the manufacture of sections of circular cross-section,

   the final pair of rollers comprises grooves delimiting a cross-section approximately corresponding to that of the section desired,

   the cross-section formed by the grooves of the final pair of rollers has at the apexes of the polygon radii of curvature between 1 and 5 mm,

   the sides of the polygon non parallel to the gap of the final pair of rollers have, relative to the corresponding sides of the cross-section of the final section a clearance between ½ and 3°.
2. A process according to claim 1, characterised in that the section has a square or rectangular cross-section.
3. A process according to claim 2, characterised in that the section has a rectangular cross-section section with a width/thickness ratio >4.
4. A process according to claim 1, characterised in that the section has a triangular cross-section.
5. A process according to claim 1, characterised in that the section has a T-shaped or V-shaped cross-section.
6. A process according to any one of claims 1 to 5, characterised in that the rollers of the penultimate pair have a plane surface.
7. A process according to any one of claims 1 to 6, characterised in that it is followed by at least one discontinuous or continuous wire drawing pass and possibly by at least one annealing.
8. A process according to claim 7, characterised in that the number of drawing passes and the number of annealings are each reduced by at least one third relative to a process which would use as an as-cast bar for discontinuous or continuous wire drawing a wire rod of approximately circular cross-section to obtain a similar product.
9. A process according to claim 8, characterised in that the section is made of an aluminium alloy, of square or triangular cross-section and that the process includes only one discontinuous or continuous wire drawing pass and only one annealing.
10. A process according to claim 9, characterised in that the aluminium alloy is an alloy of the 5000 series.
11. A process according to claim 10, characterised in that the aluminium alloy is a 5756 alloy.
12. A process according to claim 8, characterised in that the section is made of an aluminium alloy of rectangular cross-section with a width to thickness ratio between 2 and 5, and that the process includes at least 3 discontinuous or continuous wire drawing passes and 2 annealings.
13. A process according to claim 12, characterised in that the aluminium alloy is an alloy of the 2000 series.
14. A process according to claim 13, characterised in that the aluminium alloy is a 2017 alloy.
15. A process according to claim 8, characterised in that the section is made of an aluminium alloy of rectangular cross-section with a width to thickness ratio between 1 and 2, and that the process includes at least 2 discontinuous or continuous wire drawing passes and one annealing.

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