MXPA97006304A - Process of elaboration of a sheet or of a steel band for the manufacture of a can and steel sheet obtained by this procedimie - Google Patents

Abstract

The object of the invention is a method for manufacturing a sheet or band intended for the production of a can obtained by embossing-reviewing from a steel having a composition in percentage of the following weight: Carbon less than 0.008%; Manganese understood between 0.10 and 0.30%; Nitrogen less than 0.006%; Aluminum understood between 0.01 and 0.06%; Phosphorus less than 0.15%; Sulfur less than 0.020%; Silicon less than 0.020%; a maximum of 0.08% of one or more of the elements chosen among copper, nickel and chromium, the rest is iron and residual impurities, procedure by which roughing is laminated under heat in a sheet under heat or a strip thickness less than 3mm, then the sheet under heat or the strip is laminated under cold with a reduction rate between 83 and 92% and subjected to a recrystallization anneal at a temperature lower than Acl and again laminated under cold with a rate of reduction included in e 10 and 4

Description

PROCEDURE FOR ELABORATING A SHEET OR A STEEL BAND FOR THE MANUFACTURE OF A CAN AND STEEL SHEET OBTAINED BY THIS PROCEDURE.

The present invention relates to the process of making a sheet or a steel band for the manufacture of a can obtained by stuffing-review of the can type for drink.

The subject of the present invention is also a sheet or a strip of steel intended for the manufacture of a can obtained by embossing-reviewing.

This type of cans generally has a bottom and a peripheral skirt and a neck to make the setting of a cover, which can be easily opened and is manufactured particularly by inlay-review from a cupela cut into a sheet or a band .

For this purpose, the cup first passes through a sausage by relatively serious pressing on a press in a conventional manner, it has a part with a fixed punch and a support that forms a peripheral clamp that slides around the punch and on which the cup and cup rests. On the other hand, a matrix destined to be applied on the REF: 25382 cupela according to a force transmitted vertically by an upper slide.

The cup having a bottom and an edge formed with the operation of the sausage is afterwards or calibrated by a slight sausage without the use of a fastener, that is, re-blended with a fastener, and is subjected to a revision operation consisting of stretching by means of stretching bench, by successive reductions the edge to progressively form the peripheral skirt of the can.

Then the bottom is formed on the stretch bench to confer a certain geometry and the neck of the peripheral skirt is formed according to two techniques or a technique of narrowing with a matrix or a narrowing technique by means of a moleta.

The technique of matrix tightening consists in forcing the neck into a matrix that has a conical entrance profile and a cylindrical outlet profile. A cylindrical piece ensures the guiding of the wall formed in matrix outlet.

The force required to allow deformation of the metal comes from the push applied on the bottom of the can and transmitted axially by its peripheral skirt.

In order to achieve the desired inner diameter, several successive reductions are necessary, each one being a different molding stage, when the reduction of the diameter is obtained, the binding is generally done with knurls.

The technique of tightening by means of a pin consists of keeping the can in rotation that is maintained between a pusher and a centering ring.

The free end of the peripheral skirt is introduced on a mandrel and two molars that move axially and form the neck of the can that is gradually released from the mandrel being held between the pusher and the centering ring.

The profile of the neck is obtained by the simultaneous displacements of the molars, the centering ring and the pusher.

After these different operations, the can is filled and covered, for example for easy opening, it is crimped on the neck of said can.

It is known that for the manufacture of this type of can it uses a sheet or a band of steel called extra-soft and whose composition in percentage of weight is as follows: i Carbone of the order of 0.030 to 0.040% Manganese of the order of 0.15% to 0.25% Nitrogen of the order of 0.004% to 0.006% Aluminum of the order of 0.03% to 0.05% Phosphorus less than 0.015% Sulfur less than 0.020% Silicon less than 0.020% It has a maximum of 0.08% of one or more of the elements chosen between copper, nickel and chromium, the rest is iron and residual impurities.

The sheet or the band is made by a process in which the roughing coming from a continuous casting is laminated under heat and laminated under cold to obtain a strip that is subjected to an annealing of recrystallization at a temperature lower than AC1.

This procedure makes it possible to obtain a strip that has a final thickness of about 0.30 mm and to make from this strip a can whose wall of the peripheral skirt after the sausage-review has a thickness of more or less 0. lmm Now, the manufacturers of cans, with a concern of savings and increased productivity, seek to manufacture cans of a reduced weight, ie with thinner walls thickness.

So that the can with thinner walls can resist the internal pressure of the liquids it contains, in particular when it is a carbonated drink, and so that the can itself has a sufficient mechanical content, it is necessary to use steels whose mechanical characteristics are higher.

To increase the mechanical characteristics, the industrialists have, from an extra soft steel whose composition was mentioned, to submit a roughing to a laminate under heat and a cold rolled to obtain a strip that is subjected to an annealing of recrystallization at a temperature lower to Acl, and then it is rolled again under cold.

We know that the reduction of the thickness or an increase of the mechanical characteristics of the sheets or of the bands increases the possibilities of folds at the moment of the elaboration of the can.

I Some tests showed that this procedure trains a decrease in the domain of the sausage of the sheet or of the band and an increase of the angle rate (corners bent) at the time of the sausage of the can.

A decrease in the domain of the sausage entails difficulties to give the shape of the bottom and is the origin of the appearance of folds during the sausage operation.

To avoid the appearance of creases, during the sausage the pressure exerted by the fastener on the side of the foil can be increased, but this increase in the pressure of the fastener poses a problem of control of the runoff of the metal during the sausage and can in fact , cause breakage or tearing of the metal, in particular at the level of connection rays.

On the other hand, the increase in the angle rate poses a problem at the moment of the extraction of the can from the stretching punch, that is to say at the moment of the said stripping operation.

In effect, this operation is performed by sliding a ring over the stretching punch so that this ring can rest on the free edge of the peripheral skirt of the can. i When the peripheral skirt of the body of the can has important angles, the stripping ring rests only on some points of said skirt and many times we see a fold of the skirt during the stripping which makes it necessary to discard the can.

To reduce the angle rate, it is known to wind the strip under heat before cold rolling and annealing in recrystallization.

But this supplementary operation has a disadvantage, because the edges of the sheet or the band are directly in contact with the environment and cool faster than the heart.

This natural cooling differential between the edges and the heart causes a heterogeneity of the mechanical characteristics of the sheet or the band. In addition, the coiling under heat imposes the formation of coarse cementite.

The coarse cementite can train the perforation of the wall of the peripheral skirt at the moment of the formation of the neck and a start of this same metal during the operation of stretching due to the hard particles in the steel. i On the other hand, the presence of hard particles in the steel causes premature wear of the different tools of the sausage and of the review.

So the industrialists, to get to reduce the thickness of the walls of the cans are confronted with important and often uneconomical problems.

The purpose of the invention is to avoid these drawbacks by proposing a method of making a sheet or a band intended for the production of a can obtained by embossing-rolling that allows reducing the thickness of the walls of the can and consequently obtaining a gain in the weight.

The object of the invention is a process for making a sheet or a band intended for the production of a can for the filling-review of a can type for drinking from a steel having the composition in weight percentage according to: carbon less than 0.008 % Manganese understood between 0.10 and 0.30% Nitrogen lower than 0.006% Aluminum understood between 0.01 and 0.06%. t Phosphorus lower than 0.015% Sulfur lower than 0.020% Silicon lower than 0.020% With a maximum of 0.08% of one or more of the elements chosen between copper, nickel and chromium, the rest is iron and residual impurities, a process by which the roughing is rolled under heat in a sheet under heat or a strip thickness of less than 3 mm, then the sheet under heat or the strip is cold rolled with a reduction rate between 83 and 92% and subjected to a recrystallization annealing at a lower temperature than Acl and again cold rolled with a reduction rate between 10 and 40%.

The invention also relates to a sheet or strip of steel intended for the realization of a can obtained by stuffing-review of can type for drink, characterized in that it is obtained by the aforementioned process.

The invention will be better understood upon reading the following description, given only by way of example.

The manufacture of a can of the can type for drink, by embutido-review consists of cutting in a sheet or band of steel one side and in embossing by comparatively serious narrowing on a press this side to form a cup.

Then the cup comprises a bottom and a calibrated edge subjected to a revision operation consisting in stretching by means of successive reductions, the edge to progressively form the peripheral skirt of the can.

The bottom is then formed to confer the determined geometry and the neck of the peripheral skirt is formed either by a narrowing technique or with a matrix or by a narrowing technique by means of a moleta.

In order to be able to manufacture a tin whose walls have very little thickness, the invention proposes to manufacture this type of can by means of this technique of embossing-reviewing from a steel, having very little carbon, counting the composition in percentage of the following weight: Carbon less than 0.008% Manganese understood between 0.10 and 0.30% Nitrogen less than 0.006% Aluminum understood between 0.01 and 0.06%, Phosphorus less than 0.015% Sulfur less than 0.020% 1 Silicon less than 0.020% At most it will count with 0.08% of one or several chosen elements including copper, nickel and chromium, the rest will be iron and residual impurities, and according to a procedure in which the slab coming from a continuous casting is laminated under heat or in a strip of thickness less than 3mm, then the sheet under heat or the strip is rolled under cold with a reduction rate between 83 and 92% and subjected to a recrystallization annealing at a temperature lower than Acl and finally laminated another once under cold with a reduction rate between 10 and 40%.

The roughing is laminated under heat in a strip of thickness comprised between 1.8 and 2.5mm and preferably between 2 and 2.4mm, then the strip is rolled under cold with a reduction rate to reach a thickness of the aforementioned strapping between 0.26 and 0.32 mm, and subjected to an annealing of recrystallization at a temperature lower than Acl and finally laminated again under cold with a reduction rate comprised between 28 and 35% to reach a thickness of the mentioned strip between 0.18 and 0.22mm.

The crystallization annealing is a continuous annealing. f To be able to make a sheet or a strip of steel of little thickness, between 0.18 and 0.22 mm and that has all the necessary properties for the manufacture of cans called embossed and repassed cans whose walls have an even thickness, until lower at 0.07mm we realized that it is necessary to use a steel that contains little carbon lower in weight percentage to 0.008% and to elaborate this steel according to the said double reduction technique, that is to say to make suffer the laminate or the laminated band under heat a laminate under cold followed by an annealing of recrystallization and a cold re-rolling.

Surprisingly, we realized that in order to obtain the optimum mechanical characteristics in order to be able to do the operations of sausage-review necessary to obtain a can whose walls have a thickness equal to 0.07mm, we had to lower the rate of reduction of the first cold rolled laminate or strip.

In effect, for example if we examine, the angle rate, of a sheet or of a steel strip made from a steel having the composition in percentage of the following weight: f Carbon 0.003% Manganese 0.204% Phosphorous 0.009% Sulfur 0.009% Nitrogen 0.003% Silicon 0.002% Copper 0.008% Nickel 0.021% Chromium 0.017% Aluminum 0.027% The rest will be iron that has undergone a lamination under heat to obtain a laminated strip under heat of thickness of 2, 3mm and laminated under cold to obtain a band thickness of 0.26mm and continuously annealed to a temperature lower than Acl and finally laminated again under cold so that this band has a thickness equal to 0.18mm, the angle rate equal to -0.2.

In contrast, a sheet or band made from the same steel, but that was laminated under heat to reach a weight equal to 8mm and laminated under cold to obtain a band thickness of 0.26mm, and continuously annealed in the same conditions and laminated again under cold to reach a thickness equal to 0, 18mm, presents an angle of t equal to -0,05, which is a coefficient very close to 0, then represents a steel that has a Very reduced propensity to form the angles.

It is then particularly important to respect the rates of cold rolling and re-rolling after annealing, so a rolling rate under high heat is applied in order to make a laminated strip under heat of thickness less than 3 mm, preferably between 1 , 8 and 2, 5mm.

In addition to this aspect that concerns the procedure for obtaining the band, it is also necessary to be able to manufacture deep-drawn cans with a very small thickness, use a steel with very little carbon On board 1 below, different steel compositions are indicated, steels A and F are very low carbon steels, ie steels whose carbon percentages are less than 0.006% and steels G and H are extra-soft steels.

«C 3 fifteen twenty Slabs each having the composition indicated in panel 1 above, were subjected to a treatment consisting of rolling under heat each slab in a strip, and in cold rolling this strip and subjecting said strip in an annealing of recrystallization at a temperature lower than Acl and finally to re-spin under cold.

The steel sheets or strips obtained by this procedure were subjected to tests in order to determine the elastic limits Re and Rm in the long and wide direction so the angle rate? C.

The results are indicated in Table 2 below. t t or ui or Ul TABLE It can be noted on this board that the steels G and H, while still satisfactory to the rolling conditions of the process according to the invention, have a coefficient Δ C remote from O- than the steels B, C, E. F In effect, steel B and steel H underwent conditions of rolling under heat, under cold, annealing and similar cold rolling. However, steel H has values of elasticity limit and superior tensile strength and above all a C much lower and much further away from 0.

Likewise, although G steel has suffered a low cold rolling rate of 86% and a re-rolling rate of 11% lower than those suffered by steel C, C steel G is farther from 0 than steel C C.

On the other hand, the rate of cold rolling of steel B which is 85% and steel D is 90.7% and these two steels have suffered the same rate of re-rolling after annealing,? C anisotropic steel D is of 0.24 and anisotropic C of steel B is -0.06.

Thus, the sheet or the strip of very low carbon steel, less than 0.008% and made by the process according to the invention, that is to say with a laminate under heat, a laminate under cold with a reduction rate comprised between 83 and 92% , and an annealing of recrystallization at a temperature lower than Acl and finally a cold re-rolling with a reduction rate comprised between 10 and 40%, has an elasticity limit in the long sense comprised between 350 and 450 MPa for a final thickness of more or less 0.22mm, between 440 and 540 Mpa, for a final thickness of more or less 0.20mm and between 500 and 600Mpa for a final thickness of about 0, 18mm.

The sheets or bands according to the invention can also be characterized in that the number of ferrite grains per mm 2 is between 10,000 and 30,000 and preferably between 15,000 and 25,000, which corresponds to a size of very small grains.

This is important due to the regularity of the characteristics of the metal along the coil and to avoid the uneconomical inconveniences linked to the sausage, to the revision and to the formation of the neck.

The method of making a sheet according to the invention also makes it possible to preserve a certain amount of carbon in solution in the sheet.

Such a sheet then exhibits the characteristics of significantly hardening during the firing of the varnish, practiced on the can after it has been put into shape.

This characteristic is very important in the case of the manufacture of the cans obtained by stuffing-reviewing because the sheet according to the method of the invention presents the mechanical characteristics suitable to favor its putting into shape, the mechanical characteristics varying little with time.

Once the can is formed, varnished and passed through the varnish firing treatment, the mechanical characteristics increase significantly which represents an advantage in increasing the mechanical characteristic of the can.

This mechanical characteristic of the can is particularly signaled by the inversion pressure of the dome at the bottom of the can.

This pressure of investment, pressure limit from which the dome made on the bottom of the can is returned, increases of the order of 10% after the drying in stove to arrive for example, for a given type of can of 6.3 at 6.9 bars.

This is particularly true in the case of 1 Relaminated under cold after the lamination of the sheet comprised between 10 and 30%.

Thus, the method according to the invention for the production of a sheet or a strip of very low carbon steel for the manufacture of a can, can type for drink, obtained by inlay-review, allows to reduce the thickness of the walls of the can and obtain a gain of weight of more or less 30% on the sheet of the band, increasing the domain of the sausage and reducing the angle rate and the risks of formation of folds at the time of the sausage of the can.

Claims (11)

REINVINDICATIONS

1. Process for making a sheet or a band for the manufacture of a can obtained by / sausage-review, of the can type for drink, from a steel that has the composition in percentage of the following weight: carbon less than 0.008% manganese, understood as 0.10 to 0.30% nitrogen less than 0.006% aluminum, understood as 0.01 to 0.06% phosphorus lower than 0.015% sulfur lower than 0.020% silicon lower than 0.020% with a maximum of 0.08% of one or more of the elements chosen among copper, nickel and chromium, the rest is iron and residual impurities, a process by which the roughing is laminated under heat in a sheet under heat or a strip thickness of less than 3 mm, then the sheet under heat or the strip is cold rolled with a reduction rate between 83 and 92% and subjected to a recrystallization annealing at a lower temperature than Acl and again cold rolled with a reduction rate between 10 and 40%.

2. Process according to claim 1, characterized in that the roughing is laminated under heat in a strip of thickness between 1.8 and 2.5mm.

3. Process according to claim 2, characterized in that the roughing is laminated under heat in a strip understood between 2 and 2.4 mm.

4. Process according to claim 1, characterized in that the strip is rolled under cold with a reduction rate, to reach a thickness of said strip understood between 0.26 and 0.32mm.

5. Procedure according to claim 1, characterized in that the strip is re-rolled under cold with a reduction rate understood between 28 and 35%.

6. Process according to claims 1 and 5, characterized in that the strip is re-rolled under cold with a reduction rate to reach a thickness of said strip between 0.18 and 0.22 mm.

7. Process according to claim 1, characterized in that the recrystallization annealing is a continuous annealing.

8. Sheet or band of steel intended for the manufacture of a can obenida by embutido-review, of type can for drink, characterized in that it is obtained by the procedure according to one of the preceding claims. 1

9. Sheet or strip of steel according to claim 8, characterized in that it has a yield strength in the long term between 350 and 450 MPa for a sheet or a band of final thickness, of plus or minus 0.22 mm between 440 and 540 Mpa through a sheet or band with a final thickness of about 0.20 mm and between 500 and 600 Mpa through a sheet or band with a final thickness of about 0.18 mm.

10. Sheet or steel band according to claim 8, characterized in that the number of ferrite grains per mm2 is between 10,000 and 30,000 and preferably between 15,000 and 25,000!

11. Use of a sheet or a steel strip by the method according to any one of claims 1 to 7, for the production of a beverage can made by embossing-review.