EP1918035B1

EP1918035B1 - Tension levelling system for a metal strip

Info

Publication number: EP1918035B1
Application number: EP07020017.5A
Authority: EP
Inventors: Serafino Cozzi
Original assignee: Selema Srl
Current assignee: Selema Srl
Priority date: 2006-10-30
Filing date: 2007-10-12
Publication date: 2019-12-25
Anticipated expiration: 2027-10-12
Also published as: EP1918035A1; ITMI20062077A1; CN101172293A; TW200819220A

Description

The present invention refers to a tension levelling system for a metal strip in particular having thickness included from 0 to 1 mm.
The known tension levelling systems provided of at least a levelling roll which is provided of an elastically expandable internal cavity through insertion within the same one of a pressurized fluid, they do not allow a fine levelling in the case of a metal strip having planarity defects in one or more transversal portions of the same one.
Objective of the present invention is that to realize a tension levelling system for a metal strip that allows the levelling of one or more transversal portions of said same metal strip.
Another objective is that to realize a tension levelling system of a metal strip that allows an increase of the levelling in transversal direction of the same metal strip.
Another objective is that to realize a tension levelling system of a metal strip which avoids the breaking of the same metal strip also in the case of metals which show a brittle behaviour.
Yet another objective is that to have a tension levelling system for a metal strip which allows a constant levelling of the metallic strip in transversal direction also with the vary of the feeding speed of the same one.
Further objective is that to have a tension levelling system for a metal strip that avoids the formation of superficial defects, what for example scratches or imprints, on said metal strip during the working.
These objectives according to the present invention are reached by providing a tension levelling system of a metal strip as specified in claim 1.
Other features of the invention are pointed out in the following claims.
The features and the advantages of a tension levelling system for a metal strip according to the present invention will appear more evident from the following illustrative and not limitative description, referred to the attached schematic drawings in which:

figure 1 is a raised side schematic view which shows a preferred form of embodiment of a tension levelling system according to the present invention;
figure 2 is a raised side schematic view which shows a second preferred form of embodiment of a tension levelling system according to the present invention;
figure 3 is a raised frontal partially sectioned schematic view of a preferred form of embodiment of a levelling roll in a rest configuration of the tension levelling system shown in figures 1 and 2;
figure 4 is a raised frontal schematic view of a detail of figure 3;
the figures from 5 a 9 are frontal raised sectioned details of a preferred form of embodiment of a levelling roll according to the present invention in various deformed configurations.

With reference to the figures, it is shown a tension levelling system 10 for a metal strip 14 able to work also metal strip which shows a brittle behaviour avoiding the breaking of the same, as for example hardened aluminium alloys.
Said tension levelling system 10 comprises at least a couple of levelling rolls 50 of which at least one having an internal cavity 55 elastically expandable through insertion into the same of a pressurized fluid.
According to the present invention said at least one levelling roll 50 of a couple of levelling rolls is provided with an internal cavity 55 which comprises sealing means suitable to divide said internal cavity 55 in a plurality of chambers 60 each of which is expandable in independent way through insertion of a pressurized fluid.
Said sealing means comprise preferably a plurality of sealing elements 71 suitable to divide said internal cavity 55 in said plurality of chambers 60.
Preferably said plurality of sealing elements 71 is a plurality of annular gaskets.
Furthermore said sealing means comprise preferably a plurality of retaining element 72 each of which is in particular associated to a correspondent sealing element 71 in order to avoid the extrusion of the same within said internal cavity 55.
In particular said sealing means comprise at least a couple of annular gaskets 73 which preferably are positioned respectively in proximity of a first and a second extremity of said internal cavity 55.
Preferably said plurality of chambers 60 is positioned along a transversal direction 15 within said internal cavity 55.
Preferably said at least one levelling roll 50 provided with an internal cavity 55 comprises a plurality of input/output ducts 62 for a pressurized fluid every of which it is respectively connected to a chamber 60 so that to be able to expand the same independently from the other chambers 60.
Furthermore in particular said plurality of input/output ducts 62 is connected to a pump 80 of which said tension levelling system 10 is preferably provided.
In particular said levelling roll 50 also includes a plurality of electrovalves 65 connected to a command and control system, not shown, each of which allows when activated the passage of a pressurized fluid within a correspondent input/output duct 62 in such way to make expand a correspondent chamber 60.
Each chamber 60 is expandable in independent way from the others through a pressurized fluid and it is able to elastically deform a correspondent external portion 56 of said levelling roll 50 in such way to modify an external profile 57 of the same.
This, in particular along a transversal direction 15, orthogonal to a feeding direction of said metal strip 14.
Each chamber 60 shows an annular form substantially axial symmetric respect to the axis of said levelling roll 50 provided with internal cavity 55.
According to a preferred form of embodiment said levelling roll 50 provided with internal cavity 55 include an internal roll 51 and a tubular mantle 53 which is shrinked on said inside roll 51 so that to define said internal cavity 55.
Said internal roll 51 includes preferably a plurality of seats 54 suitable to house respectively a correspondent sealing element of said plurality of sealing elements 71.
Furthermore said plurality of seats 54 is preferably a plurality of annular grooves obtained on an external surface 52 of said internal roll 51, which are in particular uniformly distributed on said same external surface 52.
Preferably said internal roll 51 comprise a plurality of helical grooves 66 obtained respectively within each chamber 60 on said external surface 52 of said same internal roll 51 in order to allow a best distribution of said pressurized fluid within each same chamber 60.
Preferably said at least one levelling roll 50 provided with internal cavity 55 includes two sealing flanges 59 which are in particular made integral to said internal roll 51 and besides they constrain axially said mantle 53 avoiding therefore a disassembly of the same with respect to said internal roll 51 in the case in which one or more chambers 60 are activated in expansion.
In particular said at least one levelling roll 50 provided with an internal expandable cavity 55 comprises at least a couple of recovery conduits 64 of said pressurized fluid preferably positioned in proximity of the extremities of said internal cavity 55.
According to a second preferred form of embodiment of the present invention said tension levelling system 10 includes at least a couple of levelling rolls 50 both provided respectively of an expandable cavity 55 having one or more features of the type previously described.
In other terms according to a preferred form of embodiment of the present invention said at least a levelling roll 50 provided with internal expandable cavity 55 are two levelling rolls provided of an internal cavity 55 both having one o more features of the type previously described.
Advantageously in this way it is possible to modify the external profile 57 of said at least a levelling roll 50 provided with internal cavity 55 in such way to level defects present in one or more transversal portions of said metal strip 14.
In fact expanding one or more chambers 60 is in fact possible to pass from a rest configuration, in which said external profile 57 of said levelling roll 50 result in linear configuration, to a deformed configuration in which said profile 57 can assume various forms what for instance concave forms, conic forms, convex forms and also more complicated as shown in the figures by 5 to 9, in such way to be able to level defects present in one or more transversal portions of said metal strip 14.
According to the present invention said system 10 includes a plurality of tension rolls, not shown, that sets in tension said metal strip 14 maintaining the level of stress on the same in the elastic strain field.
Besides said tension levelling system 10 includes a plurality of stretching rolls 30
which increase the level of stress on said metal strip 14 in order to arrive to a level of stress correspondent to the stress limit in the elastic strain field.
Said levelling system 10 includes besides regulating means of the level of stress which reduces in case of increase of the level of stress on the metal strip 14 the same stress.
In particular said regulating means of the level of stress are suitable to check and to regulate in speed said stretching rolls 30 so that to avoid advantageously sudden increases of the level of stress over the yield limit.
Besides advantageously each levelling roll 50 being preferably freewheel, or rather free to rotate, it doesn't create variations of stress on said metal strip 14.
In fact it is to notice that the expansion of one or more chambers 60 determine variations in radial sense of very small quantity of the order of the tenths of mm.
In this way instead to stretch said metal strip 14 said at least one couple of levelling rolls 50 maintains the level of stress on the same to a value next to that of the yield limit however for a very long time.
Advantageously there is, with reference to the figure 2, only an area, inclusive among said plurality of stretching rolls 30, in which plastic deformation is present and in which said metal strip is submitted to a stress substantially equal to that of the yield limit for a very long time, such to allow a best plastic slide of the crystalline grains determining therefore also a better planarity of said metal strip 14.
Preferably said plurality of stretching rolls 30 and said at least one couple of levelling rolls 50 are positioned substantially crossed.
Preferably said metal strip 14 is wrapped on said plurality of stretching rolls 30 and on said at least one couple of levelling rolls 50 in such way to have a very elevated wrapping angle, in particular greater of 240°.
Advantageously in this way are avoided possible micro slidings also with elevated feeling speeds of said metal strip 14, consequently avoiding the formation of superficial defects what for instance scratches or imprints on said metal strip 14 that would compromise the superficial quality of the same one.
Advantageously in this way it is possible to obtain a good levelling also with the varying of the feeding speed of said same metal strip 14.
Advantageously through said at least one modified levelling roll according to the present invention it is also possible to compensate the differences of elastic return of the various transversal portions of said metal strip consequently determining a smaller general elastic return.
In this way it has been seen that a tension levelling system of a metal strip according to the present invention achieves the objectives previously mentioned.
Furthemore, in practice the materials used, as well as their dimensions and the components, can vary according to the technical needs.

Claims

Tension levelling system (10) for a metal strip (14) comprising at least a couple of levelling rolls (50) of which at least one having an internal cavity (55) elastically expandable through insertion into the same of a pressurized fluid, further comprising a plurality of tension rolls and a plurality of stretching rolls (30), said at least one couple of levelling rolls (50) is positioned between said plurality of stretching rolls (30), said metal strip (14) is wrappable on said plurality of stretching rolls (30) and on said at least one couple of levelling rolls (50), and characterized by comprising sealing means suitable to divide said internal cavity (55) in a plurality of chambers (60) each of which is expandable in an independent way from the others through insertion of a pressurized fluid and in that each chamber (60) includes an annular form substantially axial symmetric respect to the axis of said levelling roll (50) having said internal cavity (55).
System (10) according to claim 1, characterized in that said sealing means comprise a plurality of sealing elements (71) suitable to divide said internal cavity (55) in said plurality of chambers (60).
System (10) according to claim 2, characterized in that said plurality of sealing elements (71) is a plurality of annular gaskets.
System (10) according to any one of the claims from 1 to 3, characterized in that said sealing means comprise preferably a plurality of retaining elements (72).
System (10) according to any one of the claims from 1 to 4, characterized in that said sealing means comprise at least a couple of annular gaskets (73) which are preferably disposed respectively in proximity of a first and of a second extremity of said internal cavity (55).
System (10) according to any one of the claims from 1 to 5, characterized in that said plurality of chambers (60) is positioned along a transversal direction (15) within said internal cavity (55).
System (10) according to any one of the claims from 1 to 6, characterized in that said at least one levelling roll (50) provided with internal cavity (55) includes a plurality of input/output conduits (62) for a pressurized fluid each of which is connected respectively to a chamber (60).
System (10) according to claim 7, characterized in that said at least one levelling roll (50) provided with an internal cavity (55) includes a plurality of electrovalves (65) each of which when activated allows the passage of a pressurized fluid within a correspondent input/output conduit (62) in such a way to make expand a correspondent chamber (60).
System (10) according to any one of the claims from 1 to 8, characterized in that said at least one levelling roll (50) provided with an internal cavity (55) comprises an internal roll (51) and a tubular mantle (53) that is shrinked on said internal roll (51) in such a way to define said internal cavity (55).
System (10) according to claim 9, characterized in that said internal roll (51) comprises a plurality of seats (54) suitable to house respectively a correspondent sealing element of said plurality of sealing elements (71).
System (10) according to claim 10, characterized in that said plurality of seats (54) is a plurality of annular grooves obtained on an external surface (52) of said internal roll (51).
System (10) according to any one of the claims from 9 to 11, characterized in that said internal roll (51) comprises a plurality of helicoidal grooves (66) obtained respectively within each chamber (60) on said external surface (52) of said same internal roll (51) in order to allow a better distribution of said pressurized fluid within each same chamber (60).
System (10) according to any one of the claims from 9 to 12, characterized in that said at least one levelling roll (50) provided with an internal cavity (55) includes two sealing flanges (59) which are in particular made integral to said internal roll (51) and besides they axially constrain said mantle (53).
System (10) according to any one of the claims from 1 to 13, characterized in that said at least a levelling roll (50) provided with internal expandable cavity (55) comprises at least a couple of recovery conduits (64) of said pressurized fluid.
System (10) according to any one of the claims from 1 to 14, characterized in that it comprises at least a couple of levelling rolls (50) both ones respectively provided of an expandable cavity (55).
System (10) according to any one of the claims from 1 to 15, characterized by comprising regulating means of the level of stress which reduce in the case of an increase of the level of stress on said metal strip (14) the same stress applied to said metal strip (14).
System (10) according to claim 16, characterized in that said regulating means of the level of stress are suitable to check and to regulate in speed said stretching rolls (30).
System (10) according to any one of the claims from 16 to 17, characterized in that each levelling roll (50) being freewheel, or rather free to rotate.
System (10) according to any one of the claims from 16 to 18, characterized in that said plurality of stretching rolls (30) and said at least one couple of levelling rolls (50) are positioned substantially crossed.
System (10) according to any one of the claims from 16 to 19, characterized in that said metal strip (14) is wrapped on said plurality of stretching rolls (30) and on said at least one couple of levelling rolls (50) in such a way to have an elevated wrapping angle, in particular greater of 240°.