EP0109323B1 - Method for planetary mill operation - Google Patents

Description

The present invention relates to a family of rolling methods in which the working rolls are movable in space and come into contact with the product periodically, over all or part of their trajectory.

Laminating plants built according to this principle are today well known under the name "planetary rolling mill" and have a particular design from a series of small horizontal working rolls, arranged in a "squirrel cage" rotating at great speed. speed around support rollers mounted in “duo on either side of the product.

For the sake of convenience for the following, we should qualify as "planetary - any rolling mill, whatever its design, whose working rolls meet the mobility criteria indicated above.

We know that the principle of the planetary rolling mill solves the problem of rolling products with very slow running speed (for example of the order of 1 m / min) thanks to the superposition of the movement of movement in the space of the axis. geometrical of the working cylinder with its usual rotational movement on itself, which ensures a very short contact time between the product to be laminated and the cylinder.

Apart from the known variant known as “oblique rolling”, in which the working cylinder is permanently in contact with the product, which necessarily has a periodic symmetry of revolution ((which limits its field of application singularly), main variants of planetary rolling all have in common the existence of a speed discontinuity between the orbit of the cylinder and the direction of flow of the metal to be laminated at the entrance to the rolling mill. This discontinuity results in a relatively violent shock each time a cylinder comes into contact with the product to be laminated (of the order of 2 to 3,000 times per minute), which results in very severe mechanical stresses on the material. and harsh working conditions for staff due to noise.

In one version, proposed by the company under English law "Hille Engineering", the cylinder travels its orbit up the chock of the support cage and is connected almost tangentially with the product, which should have the effect of reducing the sound level. To the knowledge of the inventor, this solution has however been proposed only for long products and requires rolling "upward (ie opposite the direction of movement of the product to be laminated), which limits the applicability of the process.

In another version, the subject of document US-A 2978933 (Senzimir), provision has been made, for reasons other than noise control, to give the working cylinder a path of contact with the product which has the shape of an "S" horizontally and which, at first glance, should be able to reduce impact noise. However, because of the very outline of this "S", the reduction in noise can only be obtained if the orbit is traveled upwards, which again limits its interest. In addition, this document teaches itself to retain only a downward rolling, this in order to traverse the plastic deformation zone of the product to be laminated in the direction of reduction of its thickness by rolling.

The object of the present invention is to solve the problem of these repetitive shocks of the noise disturbances specific to the planetary rolling mill by means of a solution which does not have the drawbacks of the known methods.

To this end, the subject of the invention is a method of driving a planetary rolling mill according to which, the direction of rolling of the product to be laminated being assumed to be horizontal, the working cylinder is made to pass an orbit over a portion of which it is maintained in contact with the product to be rolled, the cylinder trajectory on said portion being in the form of an "S" horizontally, process characterized in that, the cylinder being able to traverse its orbit in one direction or the other, said trajectory is limited by two points (A and B) where the tangents (Ta and Tb) to the orbit are parallel to each other and to the direction of rolling of the product.

• - la figure 1 est un schéma de principe du procédé, montrant la portion de l'orbite du cylindre de travail au contact du produit,
• - les figures 2, 3 et 4 sont des schémas de principe montrant différentes variantes de réalisation d'un dispositif pour la mise en oeuvre du procédé.

The invention will be better understood and other aspects and advantages will appear more clearly in the light of the description which follows, given with reference to the plates of attached drawings, in which:

• FIG. 1 is a block diagram of the process, showing the portion of the orbit of the working cylinder in contact with the product,
• - Figures 2, 3 and 4 are block diagrams showing different alternative embodiments of a device for implementing the method.

In Figure 1, there is shown at 1 a working cylinder whose axis 2 traverses an orbit 3 in a closed loop. For a better understanding of the invention, only the part of the orbit close to the product to be laminated 5 is shown in the figure.

More precisely, the portion 4 of this orbit, the portion along which the cylinder 1 is in contact with the product 5, has a trajectory in the form of an "S" at the horizontal limited by two extreme points A and B where the tangents T _A , Tε at orbit 3 carried at these points are parallel to each other and parallel to the rolling direction of product 5, indicated by the arrow V in the figure and which, in practice, can generally be considered as perfectly horizontal.

The trajectory 4 advantageously has an inflection point 1 to ensure a regular displacement of the cylinder 1 between the extreme points A and B.

To allow rolling, an opposing system A'I'B 'is arranged symmetrically to the first AIB system with respect to the product to be laminated 5. We find in this opposing system A'I'B 'the same elements and arrangements, as in the AIB system identified by references which are differentiated only by the sign "prime". The axes 2, 2 'of the working rolls 1, 1' are horizontal and perpendicular to the plane of the figure. We therefore see that the thickness of the rolled product 5 is thus reduced by the quantity 2d (d being the distance separating the tangents T _A and T _B - respectively TA 'and T _B ' -), when the cylinders 1 and 1 'travel their respective arc AB and A'B '.

These cylinders can travel their arc in one direction or the other, it being understood that they move simultaneously in the same direction. In the following description, we will consider, for simplicity, only the displacement of the upper working cylinder 1. When, as shown in the figure, this cylinder traverses the arc AB from A to B, it comes into contact with the product 5 at A and leaves at B. Between these two points, contact with the product is permanent to exert the rolling force, and the cylinder rolls on the surface of the product, in the direction of rotation indicated by the arrows.

• - ou se poursuivre, de l'autre côté de la tangente T_A, sans modification sensible de la direction du secteur vitesse, le point A étant alors un point d'inflexion (variante repérée par la lettre cerclée @ sur la figure),
• - ou, selon une autre variante, se poursuivre avec inversion du sens du secteur vitesse, le point A étant dans ce cas un point de rebroussement (variante repérée par la lettre cerclée @ ).

In accordance with the invention, the part of orbit 3 located beyond point A, ie the part of the path taken by axis 2 just before the cylinder comes into contact with the product to be laminated at A, can:

• - or continue, on the other side of the tangent T _A , without appreciable modification of the direction of the speed sector, the point A then being an inflection point (variant identified by the letter circled @ in the figure),
• - or, according to another variant, continue with reversing the direction of the speed sector, point A being in this case a cusp point (variant identified by the circled letter @).

Whatever the variant used, the trajectory of the cylinder 1 tangentially connects the surface of the product to be laminated 5 and there can therefore be no shock.

It goes without saying that the preceding provisions also apply with respect to point B if it is desired to laminate the product 5 by "going up", that is to say if the cylinder 1 must traverse its working arc AB in the direction from B to A. In this case, however, it should be observed that the connection at B is not strictly tangential to the surface of the product 5 due to the slight advance of the latter during the time when the cylinder 1 loops its orbit 3 from A to B outside of the portion 4 (case where the orbit 3 is traversed entirely always in the same direction). A very slight shock may therefore occur at B, but the noise level of which remains incommensurate with the noise caused by existing known processes.

On the other hand, in the case where the working arc AB is traversed alternately from A to B then from B to A, the cylinder 1 therefore remains permanently in contact with the product to be laminated 5 and there will consequently be no shock .

Furthermore, in order not to risk adversely affecting the good surface quality of the laminated products, it is advantageous to avoid slippage of the cylinder on the product when it comes into contact.

To this end, in accordance with a preferred implementation of the invention, the cylinder is printed, when it comes into contact with the product, a speed of rotation equal to, or in any case close to, that which corresponds to the conditions of rolling of the cylinder on the product to be laminated (this being defined, therefore predeterminable as we know and as we know how to calculate it, from the speed of the product to be laminated, and the value and direction of the speed of the cylinder on its orbit upon contact with the product).

Of course, in the case of variant ⓑ, the speed of movement of the cylinder being necessarily zero at the time of coming into contact with A (since the latter is a cusp), the speed of rotation of the cylinder around its axis 2 will advantageously be zero at this time also.

Likewise, the possible problems of synchronization of the speed of rotation of the cylinder at the time of contact does not arise in the case where the working arc is traversed alternately from A to B then from B to A, since the working cylinder then remains permanently in contact with the product to be laminated.

Whichever variant is chosen, the working cylinder is rotated about its axis 2 under the effect of cissions which arise on contact with the rolled product. Energy is supplied by the motors controlling the system which generates the movement of the cylinder in its orbit.

In the case of conventional multi-cylinder planetary rolling, as mentioned at the beginning, the horizontal component of the resultant of the forces acting along the contact arc AB is directed in the opposite direction to that of rolling, which has the effect a rearward discharge of the material to be laminated. This force must therefore be balanced by a pusher member which is generally a first “ordinary duo” cage placed upstream of the planet with respect to the direction of rolling and which imposes on the product to be laminated a law of displacement, said force being maximum at the time when the working cylinder comes into contact with the product.

In the method according to the invention, the shape of the horizontal “S” of the contact arc AB is such that this thrust force is minimal when the contact of the cylinder with the product 5 is established, which has the effect of minimizing the stresses on the thrust member imposing the law of advance of the product to be laminated.

The device ensuring the movement of the working rolls in an orbit 3 according to the invention is produced by combination of eccentrics and connecting rods, three different embodiments of which are shown in FIGS. 2, 3 and 4 respectively.

Figures 2 and 3 each illustrate a device designed to allow the working cylinder 1 to travel through its orbit 3 entirely in the same direction (direction indicated by the arrows).

The device represented in FIG. 2 essentially consists, as can be seen, of three connecting rods 21, 22 and 23, of three eccentrics 24, 25 and 26 and of a connecting rod 27.

Each connecting rod is articulated at one of its ends (respectively 28, 29, 30) to an eccentric (24, 25, 26). The connecting rod 21 is fixed at its other end to the axis 2 of the working cylinder 1. The other two connecting rods 22, 23 form at their end a rotary torque M and the rod 27 connects this mobile point M to the axis 2. The trees of the three eccentrics rotate in the direction indicated by the arrows. The rotational speeds are equal in absolute value, their ratios being kept fixed, for example by means of gears not shown in the figure. One of the eccentrics is driven by a motor also not shown.

Under these conditions, the axis 2 of the working cylinder traverses the contact arc AB from A to B by making contact with the product at A, this point constituting a cusp point (type 0 variant).

The device shown in Figure 3 comprises only two connecting rods 31, 32 and two eccentrics 33, 34. The connecting rod 31 is connected to the axis 2 of the working cylinder and is extended beyond its point of articulation 35 on the eccentric 34 to a movable point N forming a couple with the connecting rod 32 at its end opposite to that of its attachment 36 on the eccentric 33. The two eccentrics rotate in opposite directions, as indicated by the arrows, the the rest being unchanged compared to the device described with reference to FIG. 3.

Under these conditions, the axis 2 of the cylinder 1 traverses the working arc AB from A to B by contacting the product at A, this point constituting a point of inflection (variant of type (S)).

The device shown in Figure 4 is similar to that of Figure 2. There are, according to the same organization, a set of three connecting rods 41, 42, 43 and three eccentrics 44, 45, 46, a connecting rod 47 and the joints 48, 49, 50 between the eccentrics and the connecting rods, as well as the movable point M connecting the connecting rods 42, 43 and the rod 47 in a common torque.

Unlike, however, the device shown in FIG. 2, one of the eccentrics, in this case the eccentric 46 in the example shown, is driven in an alternating rotational movement less than one revolution, by a fourth eccentric 51 using an additional connecting rod 52, the eccentric shaft 53 being driven in continuous rotation by a motor.

Under these conditions, the axis 2 of the working cylinder 1 traverses the working arc AB alternately from A to B then from B to A (rolling by "going up in the latter case) and the cylinder therefore remains permanently in contact with the laminate 5.

Of course, the invention cannot be limited to the examples described, but extends to multiple variants or equivalents insofar as the characteristics set out in the appended claims are respected.

Claims (5)

1. A method for operating a planetary mill by which, assuming a horizontal rolling direction of the product to the rolled (5), the working cylinder (1) is made to travel in an orbit (3) on a portion (4) of which it is held in contact with the product to be rolled, the path of the cylinder on said portion having the shape of a horizontal c S -, characterized in that, the cylinder being able to travel in its orbit (3) in one direction or the other, said path is limited by two points (A and B) where the tangents (Ta and Tb) to the orbit (3) are parallel to each other and to the direction of rolling of the product.

2. A method according to claim 1, characterized in that the point (A or B) of the portion (4) where the cylinder (1) comes in contact with the product to be rolled (5) is a reversal point of the orbit (3) of displacement of said cylinder.

3. A method according to claim 1, characterized in that the point (A or B) of the portion (4) where the cylinder (1) comes in contact with the product to be rolled (5) is a stationary point of the orbit (3) of displacement of said cylinder.

4. A method according to claims 1, 2 or 3, characterized in that the portion of the path (4) has a reversal point (1) between its two extreme points (A and B).

5. A method according to claim 1, characterized in that a rotational speed about its axis (2) is communicated to the cylinder (1) at the moment of its contact with the product to be rolled (5), said speed being equal or substantially equal to that corresponding to the rolling conditions of the cylinder on the product in the course of rolling.

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