Patent Application
20120174644
The invention relates to a machine for leveling thick metal plates or strips that, henceforth, shall be referred to generically as “strips”.
Leveling devices, known as levelers, are used to remove flatness defects in strips following hot or cold rolling. Indeed, for example after the hot rolling, cooling and conditioning phases, the rolled products may have non-developable flatness defects, such as defects known as edge wave or center buckle, or developable flatness defects, such as bowing defects. These geometric defects visibly affect rolled products.
Levelers with multiple rollers arranged such that they overlap, establishing an undulating route for the strip, which is then subjected to bending effects in alternating directions, are used to level such rolled metal strips.
A metal plate or strip leveling installation comprises, in general, a lower leveling cassette and an upper leveling cassette, each fitted with a plurality of leveling rollers that are in direct contact with the strip. These leveling rollers are usually supported by support rollers.
These two leveling cassettes are included in the structure of the leveler which comprises vertical beams, the bottoms of which are rigidly connected by a generally fixed back plate and the tops of which are rigidly connected by horizontal upper beams.
The lower cassette is supported by the lower back plate and the upper cassette is supported by a pressure frame to which it is bolted.
Most commonly, the lower cassette is fixed and the upper cassette can move vertically in order to adjust the gap between the leveling rollers and thereby determine the undulating route of the strip. This gap and the transfer of the cassette separation stress, attributable to the resistance of the strip, are effected by hydraulic closing cylinders bearing on one side against the upper beams and on the other against the pressure frame.
A motorized drive system makes it possible to actuate the rollers in rotation and, by friction, to move the strip forward at a given speed. This involves at least one motor driving at least one reduction gear that actuates at least one gearbox at the required speed that distributes the rotation torques to the different lower and upper leveling rollers by means of spindles connected at one end to the outputs of the gearbox and at the other end to the end trunnions of the rollers.
In order to offset the bending of the cassettes, the lower back plate and the upper pressure frame caused by the separation stress attributable to the passage of the strip, several systems have been invented, such as using bend correction cylinders between at least the upper cassette and the pressure frame thereof. Thus, the leveling machine shown in
Other solutions for correcting the bending of cassettes, the lower back plate and the upper pressure frame under the separation stress caused by passage of the strip have been invented. Accordingly, document EP 0 570 770 discloses the use of cylinders arranged between the upper leveling rollers and the upper pressure frame of a leveling machine. These cylinders enable the bending of the leveling rollers occurring during passage of the strip of material between the rollers to be offset. These offsetting rollers act in conjunction with cylinders enabling an upper frame with a rigidly connected upper leveling cassette to be moved. The leveling machine is also fitted with a plurality of sensors measuring the deformation of the rollers and providing information to a processor that controls the offsetting cylinders and the cylinders enabling the frame to be moved.
Document JP A 2000 326012 also discloses a leveling machine comprising a plurality of offsetting cylinders installed between an upper frame and the upper rollers of a leveling machine. Other cylinders bearing against horizontal cross members change the position of the upper leveling rollers by acting on the upper back plate of the leveling machine.
Document U.S. Pat. No. 5,461,895 discloses a leveling machine that, to offset the longitudinal bending of the leveling rollers, comprises a combination of pressure cylinders acting on the middle of the upper cassette and traction cylinders acting on the extremities thereof.
The use of an increasing number of closing and correcting cylinders complicates leveling machines and increases the height of said machines as several levels of these cylinders are stacked. Accordingly, known leveling machines comprise a stack of superimposed layers formed by an upper cassette, bend correction cylinders, the pressure frame, main closing cylinders and upper horizontal cross members. A leveling machine for very wide, thick strips can weigh more than 600 tons and be more than ten meters high. A pressure frame on its own may weigh more than 70 tons. It is therefore important to minimize the mass and size of leveling machines.
The invention is intended to address the problems identified above and, in particular, to limit the stacking of structural members and cylinders in order to limit the height of the machine and, in particular, the length of the vertical beams. It is also intended to provide a leveling machine of lesser volume and mass than known leveling machines, while fulfilling the same functions and, in particular, enabling the bending of leveling cassettes caused by the passage of the material being leveled to be offset.
In consideration of these objectives, the first object of the invention is a machine for leveling a strip of material comprising:
According to other advantageous characteristics:
The invention also relates to a flexible leveling cassette the thickness of which varies between a maximum value and a minimum value, and that is intended to cooperate with a leveling machine as defined above.
Advantageously, the leveling cassette comprises a plurality of maximum-thickness zones intended to cooperate with the closing cylinders of the leveling machine, the maximum-thickness zones being separated from one another by a minimum-thickness zone.
Furthermore, the maximum thickness value may be between 1.5 and 4 times the minimum thickness value and may preferably be between 2 and 2.5 times this value.
The total height of the leveling machine according to the invention is therefore less than known machines and, unlike leveling machines in the prior art, it does not have conventional pressure frames or horizontal cross members, which saves tens of tons from the structure and lightens the leveling machine according to the invention.
Furthermore, in relation to leveling machines in the prior art, the invention also enables the retraction cylinders to be removed from the pressure frame and the upper cassette, which represents a significant saving as these cylinders, of which there are normally four, have to be powerful enough to lift a mass of up to around 100 tons. Furthermore, they usually have significant travel in order to enable the closing cylinders to be disassembled. These cylinders are therefore very heavy and require the implementation of high-pressure hydraulic circuits and a significant quantity of oil. Removal of all of these devices has the additional effect of reducing the mass of the leveling machine by several tens of tons.
Other characteristics and advantages of this invention are set out in a detailed non-limiting embodiment provided with reference to the figures, in which:
It should be noted that the figures only show the elements required to understand the invention, it being understood that the leveling machine includes all of the elements (not shown) required to drive the leveling rollers in rotation.
The leveling machine according to the invention shown in
The leveling machine also comprises closing cylinders 10 attached firstly to the fixed upper back plate 11 and in contact secondly with an upper face of the upper leveling cassette 5a. When deployed, the closing cylinders 10 bear against the back plate 11 and force the rollers 51a of the upper leveling cassette 5a against the material to be leveled. The closing cylinders therefore cause firstly the rollers 51a of the upper leveling cassette and the rollers 51b of the lower leveling cassette 5b to move closer together and secondly, as a function of the relative vertical movement thereof, they offset the bending of the upper leveling cassette 5a caused by the separation stress generated by passage of the strip to be leveled.
Coupling means 9 attach the upper leveling cassette 5a to the back plate 11, while enabling vertical movement of the upper leveling cassette 5a under the action of the closing cylinders 7.
Each movable part 114 is fixed to an axle of the back plate 11 and can turn about this axle, each axle being supported by a flange 1100 of the back plate 11. At least one additional cylinder 115 able to pivot at least one movable part 114 extends between one extremity of the movable part 114 and one other flange 1200 of the back plate 11.
To remove the leveling equipment 5a and 5b, the rods of the closing cylinders 10 extend until the upper leveling cassette 5a is resting on the lower leveling cassette 5b. The rods 111a and 112a of the retaining cylinders 111, 112 follow the movement of the upper leveling cassette 5a downwards. Once the upper leveling cassette 5a is resting on the lower leveling cassette 5b, the rods 111a and 112a of the retaining cylinders 111, 112 continue their downward movement until each retaining hook 56a is released. By retracting, the additional cylinder 115 pivots the supporting element 114 which retracts the cylinder 112 upwards and the upper leveling cassette can be removed in the direction of the arrow 1300, from the side opposite the drive side of the leveling rollers 51a.
As mentioned previously, in leveling machines in the prior art, the pressure frame is guided between the vertical beams and the upper leveling cassette is coupled thereto using devices that follow the movements of the bend correction cylinders. In order to prevent double vertical guidance of the pressure frame and the cassette, which may cause butting and jamming, the upper cassette is not guided between the vertical beams or between the uprights of the lower cassette. In the machine according to the invention, the absence of the pressure frame enables the cassette to be guided itself between the vertical beams or between the uprights of the lower cassette, which considerably improves the precision of the movements thereof.
In general, each vertical beam 2a, 2b has an inner vertical contact surface 21a intended to cooperate with another contact surface to guide at least one leveling cassette 5a, 5b of the leveling machine in translation.
More specifically, the lower leveling cassette 5b includes vertical uprights 55b extending upwards from the base of the lower cassette 5b to guide it outside the leveling machine during assembly and disassembly operations. Each upright 55b includes an outer vertical surface 59 in contact with an inner vertical surface 21a of one of the beams 2a, 2b such as to ensure a precise positioning and to guide the lower leveling cassette 5b in translation. The uprights 55b and the lower leveling cassette 5b are therefore connected by a sliding joint. The two contact surfaces 59 and 21a extend at least partially facing one another.
Furthermore, each upright 55b of the lower leveling cassette 5b is positioned such as to act as a translational guide for the upper leveling cassette 5a. Consequently, each upright of the lower leveling cassette 5b also includes an inner vertical surface 57b in contact with an outer surface 55a of the upper leveling cassette. The contact surfaces 55a and 57b, extending at least partially facing one another when the leveling machine is fully assembled, cooperate to guide the upper leveling cassette 5a in translation in relation to the lower leveling cassette 5b. As the upper leveling cassette 5a is framed by the uprights 55b, the upper and lower leveling cassettes are therefore linked by a sliding joint which guarantees the relative positioning thereof to a high degree of accuracy. Furthermore, each outer contact surface 55a of the upper leveling cassette may be slightly convex. This enables an inclined position of the upper cassette 5a in relation to the lower cassette 5b between the strip input side between the leveling rollers and the output side.
Furthermore, the top of each of the uprights 55b of the lower leveling cassette 5b has a positioning contact 58b intended to receive a supporting element 57a of the upper leveling cassette 5a. During the cassette removal and replacement phases in the leveling machine, each positioning contact 58b receives a supporting element 57a, which guarantees the rigid attachment of the two cassettes.
In another embodiment not shown in the figures, the lower leveling cassette 5b does not have uprights 55b and the upper leveling cassette is guided in vertical translation directly by the beams 2a, 2b of the leveling machine. Thus, each outer contact surface 55a of the upper leveling cassette 5a cooperates with an inner vertical contact surface 21a of one of the beams 2a, 2b. The lower leveling cassette 5a is therefore connected to the uprights 2a, 2b of the leveling machine by a sliding joint.
In order to limit the wear generated by friction when guiding each of the elements in the leveling machine in translation, the contact surfaces 21a, 56b, 57b and 55a may be coated with an abradable material, encouraging parts such as surface-hardened steel plates to slide against one another.
To ensure that the closing cylinders 10 are able to correctly perform the function of correcting the leveling roller bend, there should preferably be at least six of them operating between the upper back plate 11 and the upper cassette 5a. As shown in
An additional condition for the correct operation of roller bend correction is the deformation capacity of the upper leveling cassette in the same direction as the longitudinal axis of the rollers. This condition is easily satisfied when leveling thick strips, which involves very high levels of upper- and lower-cassette separation stress. In the case of thinner strips, it may be necessary to change the shape of the upper leveling cassette in order to reduce the bending inertia thereof.
The embodiment shown in
By way of example, the maximum thickness value may be between 1.5 and 4 times the minimum thickness value and may preferably be between 2 and 2.5 times this value.
| Number | Date | Country | Kind |
|---|---|---|---|
| 09290685.8 | Sep 2009 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/062659 | 9/30/2009 | WO | 00 | 3/29/2012 |
