Multi-strand pinch roll

Abstract

 The present invention discloses a multi-strand pinch roll and a pinching method, wherein said multi-strand pinch roll comprises an upper roller (1) and a lower roller (2) configured for pinching multi-strand products (3), characterized in that at least one of said rollers (1, 2) comprises a plurality of adaptive rings (11) mounted on its outer surface, each adaptive ring (11) being designed for contacting at least one of said multi-strand products (3) during said pinching, wherein the number of said adaptive rings (11) equals at least the number of strand products (3) that have to be pinched at the same time by the multi-strand pinch roll.

Description

[0001] The present invention relates generally to multi-strand rolling mills and is concerned in particular with an improved multi-strand pinch roll and a method for pinching multi-strand products.

[0002] Pinch rolls are conventionally used in long product rolling mills to drive and/or propel strand products by squeezing of said strand products between an upper and a lower roll of the pinch roll. The pinching force and torque exerted by the pinch roll on the strand product must be carefully controlled and coordinated to avoid marking the product. Indeed, during the squeezing process, marking can result from excessive pinching force, or by an imbalance of pinching force and driving torque resulting in slippage of the rolls against the strand product surface. Moreover, in the case of multi-strand pinch roll, marking may also originate from differences in strand product sizes and shapes that are obtained after slitting of a cast product and pinched at the same time by the multi-strand pinch roll. Indeed, multi-strand products pinched by a multi-strand pinch roll have generally sizes and shapes that are similar, but unfortunately not identical. Due to these differences in shape and size of multi-strand products, the pinching of the strands is not identical for each strand and causes tension in and deformation of the strand product, decreasing therefore the stability of the pinching process and the quality of the resulting strand product.

[0003] Traditionally, a multi-strand pinch roll comprises an upper and a lower cylindrical roller with parallel rotation axis, mounted one above the other, wherein a distance separating the rotation axis of the rollers and defining a gap or clearance between the outside surface of said rollers is controlled and tuned for controlling the pinching of one or a plurality of strand products feeding said gap. Generally, at least one of said roll may comprise circular grooves on its outside surface adapted for driving said strand product. Up to now, problems related to differences in size and shape of strand products in a multi-strand pinch roll are tackled by fine tuning of the slitting process that gives rise to multi-strands from a single cast product. Unfortunately, the tuning of the slitting process can only reduce but not remove completely the differences in size, shape or dimension between the strands. Consequently, there is a high probability that at least one strand product over the pinched multi-strand products will be damaged by an inadequate pinching during the pinching process, since the pinching force is not equally distributed among the strand products that are pinched at the same time.

[0004] An objective of the present invention is therefore to propose a multi-strand pinch roll and a pinching method that overcome the above-mentioned problems.

[0005] The foregoing objective is achieved according to the present invention by a multi-strand pinch roll comprising an upper roller and a lower roller configured for pinching multi-strand products, characterized in that at least one of said rollers comprises a plurality of adaptive rings mounted on its outer surface, notably at least two adaptive rings, each of said rings being designed for contacting at least one of said multi-strand products during pinching, wherein the number of said rings equals at least the number of strand products that have to be pinched at the same time by the multi-strand pinch roll, each ring having preferentially at least one degree of freedom for adapting its position on the roller it is mounted on to variations of shape in the multi-strand product it is designed to contact, in particular to variations in the geometry of a transverse section of said multi-strand product. In other words, preferentially at least one of said rollers comprises adaptive rings configured for automatically adapting their position in function of differences in section sizes of the strand products that are pinched at the same time by the present multi-strand pinch roll, wherein the contact of the adaptive ring with the pinched strand product causes the displacement of the adaptive ring, i.e. the adaptation of its position.

[0006] The present invention concerns also a method for pinching multi-strand products comprising the following steps:

• engaging multi-strand products in a gap or clearance between the outside surface of an upper cylindrical roller and the outside surface of a lower cylindrical roller of a multi-strand pinch roll, wherein at least one of said cylindrical rollers comprises a plurality of adaptive rings characterized by one degree of freedom, said adaptive rings being configured for pinching the multi-strand products by applying to said multi-strand products a pinching force;
• for each strand product of the multi-strand products that are pinched at the same time t by the multi-strand pinch roll, an automatic adaptation, according to said one degree of freedom, of a position of at least one of said adaptive rings in function of the strand product section shape and size in order to equally distribute at said time t the pinching force acting on each strand product.

[0007] Preferentially, each adaptive ring has solely one single degree of freedom compared to the roller. Said degree of freedom is in particular provided by means of coupling which are configured for coupling said adaptive rings to the roller. In particular, each roller comprising said adaptive rings comprises a cylindrical shaft on which is mounted and fixed a bearing assembly that supports said adaptive rings and cooperates with the means of coupling on one hand for granting to said adaptive rings at least said one degree of freedom, and preferentially solely said one degree of freedom compared to the roller, and on the other hand for maintaining said adaptive rings on the roller while keeping said one degree of freedom. The cylindrical shaft might be designed for being driven into rotation around its rotation axis by some driving means known by people skilled in the art. Off course, the rotation axis of the shaft and the rotation axis of the roller are the same, as well as the rotation axis of the adaptive ring when the latter is mounted on the roller.

[0008] Other objectives, features and advantages of the present invention will be now described in greater detail with reference to the drawings, wherein:

Figure 1 is a longitudinal sectional view of a roller of a first preferred embodiment of multi-strand pinch roll according to the invention;

Figure 2 is an enlargement of the contact of the bottom part of Fig. 1 showing in more details the interaction between the strand products and the adaptive rings according to the invention;

Figure 3 is a longitudinal sectional view of a second preferred embodiment of a multi-strand pinch roll according to the invention.

[0009] Figure 1 illustrates a longitudinal sectional view of a preferred embodiment of a multi-strand pinch roll comprising an upper roller 1 and a lower roller 2 configured for pinching multi-strand products 3, characterized in that at least one of said rollers 1, 2 comprises a plurality of adaptive rings 11 mounted on its outer surface, notably at least two adaptive rings, each of said adaptive rings 11 comprising a rotation axis B that is identical to the rotation axis C of the roller when they are mounted on the roller, each of said adaptive rings being a working ring designed for contacting at least one of said multi-strand products 3 during pinching, wherein the number of said adaptive rings 11 equals at least the number of strand products 3 that have to be pinched at the same time by the multi-strand pinch roll, each adaptive ring 11 having at least one degree of freedom for adapting its position on the roller 1 it is mounted on to variations of shape in the multi-strand product 3 it is designed to contact, in particular to variations in the geometry of a transverse section of said multi-strand product 3. The adaptive rings 11 are preferentially mounted on a bearing assembly 5 fixed to a shaft 4 of the roller 1, said shaft 4 comprising the rotation axis C.

[0010] The plurality of adaptive rings 11 are in particular coupled to the bearing assembly 5 by means of coupling, wherein said means of coupling allow at least said one degree of freedom of the adaptive ring 11 compared to the bearing assembly 5 or roller 1. Said one degree of freedom is thus a characterization of the allowed displacement of the adaptive ring 11 according to the invention, wherein said allowed displacement is only allowed in 1 dimension. For example, Figures 1 and 2 present an adaptive ring 11 having a longitudinal degree of freedom, i.e. said adaptive ring 11 is only allowed to move according to a displacement parallel to the rotation axis C of the shaft 4 or roller 1. An adaptive ring having a radial degree of freedom i.e. that is only allowed to move according to a radial displacement with respect to roller rotation axis is presented in Figure 3. For the purpose of imposing said one degree of freedom, said means of coupling are in particular configured for allowing the adaptive rings to move solely in a direction parallel to the shaft rotation axis C in the case of the longitudinal degree of freedom, and in a radial direction perpendicular to the rotation axis of the roller/shaft in the case of the radial degree of freedom.

[0011] The bearing assembly 5 is in particular driven into rotation together with the shaft 4, and said means of coupling are configured for driving the adaptive rings 11 into rotation together with said bearing assembly 5. Preferentially, said adaptive rings 11 are mounted side by side on the roller 1, notably on the bearing assembly 5 of said roller 1, forming therefore a succession of adaptive rings 11. The first adaptive ring and the last adaptive ring of said succession of adaptive rings 11 which are notably flanking adaptive rings that are in between when said succession of adaptive rings comprises more than two adaptive rings 11 will be referred to hereafter as extreme adaptive rings 11A. Preferentially the extreme adaptive rings 11A of said succession of adaptive rings 11 are each laterally maintained by the bearing assembly 5 and/or the means of coupling, notably by a flange 51 or protuberance of the bearing assembly 5 cooperating with the means of coupling for laterally maintaining the extreme adaptive ring 11A. Said means of coupling are for example maintaining rings 6 characterized by a radius R or maintaining rods characterized by a length L.

[0012] In particular, each adaptive ring 11 has a substantially rectangular longitudinal or radial section, wherein said longitudinal or radial section is defined by the intersection of said adaptive ring 11 with a half-plane originating at the rotation axis B of the adaptive ring 11 and extending radially from said adaptive ring rotation axis B, wherein said adaptive ring rotation axis B is identical to the roller or shaft rotation axis C when the adaptive ring is mounted on the roller/shaft. Preferentially, each adaptive ring 11 of said succession of adaptive rings is identical. In particular, each adaptive ring 11 has a geometry which is symmetrical with respect to a median plane P, wherein the median plane P is perpendicular to the rotation axis B of the adaptive ring 11 and comprises the median transverse section of the adaptive ring 11, said median transverse section having substantially a shape of a circular annulus. Each adaptive ring 11 has in particular an inner surface designed for being in contact with the roller 1 or the bearing assembly 5, two side surfaces which are notably parallel to each other and have an annulus shape, and an outer surface which is designed for contacting at least one strand product. If one represents the adaptive ring as a hollow cylinder, said inner surface corresponds to the internal cylindrical surface, i.e. the surface of the hollow part of the hollow cylinder, said side surfaces are the lateral surfaces of the hollow cylinder characterized by an annulus shape, and the outer surface of the adaptive ring is the external cylindrical surface of the hollow cylinder.

[0013] Preferentially, the inner surface comprises a lubrication groove or a channel configured for the lubrication of the contact area of the adaptive ring with the roller or bearing assembly. For example, said lubrication groove is circumferentially extended on the inner surface of the adaptive ring, so that a space is managed between the bearing assembly 5 and the adaptive ring 11 at the location of said lubrication groove, said space being for example filled with a solid lubricant. In particular, said bearing assembly and said adaptive rings may also comprise one or several duct networks for feeding surfaces of each adaptive ring that are in contact with the bearing assembly and/or the means of coupling with a lubricant. Preferentially, said inner surface may also comprise at least one axial groove configured for the driving of the adaptive ring 11 into rotation by the bearing assembly 5, which may comprise an axial flange geometrically complementary to said axial groove, and adapted for the driving into rotation of said adaptive ring 11. Preferentially, said inner surface of each adaptive ring 11 and said bearing assembly 5 may each comprise at least one axial groove, wherein each axial groove of the inner surface of each adaptive ring 11 is facing an axial groove of the bearing assembly 5, each pair of axial grooves facing one another being configured for housing a parallel key 71 of the means of coupling, wherein said parallel key 71 and said axial grooves are configured for the driving of the adaptive ring 11 into rotation by the bearing assembly 5.

[0014] According to a first preferred embodiment of the present invention presented in Figures 1 and 2, each of said adaptive rings 11 has only and solely a longitudinal degree of freedom provided by said means of coupling, so that each adaptive ring 11 may for example only slide axially on the roller or bearing assembly and not radially, i.e. only in the direction parallel to its rotation axis C, B. In particular, the adaptive rings 11 are laterally maintained by said flanges 51 or protuberances of the bearing assembly 5, wherein the distance D separating the two flanges 51 or protuberances each facing one of said extreme adaptive rings 11A is greater than the sum W of the thicknesses w_i of the adaptive rings 11:


wherein A is a gap that is equal to the difference between said distance D and W. Preferentially, said means of coupling allow a repartition/distribution of the gap A between each adaptive ring 11 of said succession of adaptive rings 11 and between the extreme adaptive rings 11A and the flange 51 or protuberance they are facing:


wherein a₁ is the distance between one of said flanges 51 or protuberances and one of said extreme adaptive rings 11A and a_n+1 is the distance between the other of said flanges 51 or protuberances and the other of said extreme adaptive rings 11A, n being the number of adaptive rings 11, and a_i being the distance between the i^th adaptive ring and the i+1^th adaptive ring with 1 < i <n+1, the adaptive rings 11 of said succession of adaptive rings being successively counted from 1 to n from one of said extreme adaptive rings 11A to the other of said adaptive rings 11A, wherein each a_i ≥ 0.

[0015] For this purpose and according to a preferred embodiment, each adaptive ring 11 comprises preferentially a circular groove designed for receiving the maintaining ring 6. In particular, the circular groove and the maintaining ring 6 have a complementary geometry so that the maintaining ring 6 may at least partially fit into said circular groove. For example, the maintaining ring 6 and the circular groove have each a rectangular radial section which fit into one another, so that e.g. half of the length of the rectangular section of the maintaining ring 6 might be inserted into the groove which depth or length of its rectangular radial section equals half to the length of the rectangular section of the maintaining ring 6. In particular, each lateral side of the adaptive ring 11 comprises said circular groove, notably symmetrically disposed with respect to the transverse median plane P of the adaptive ring 11. In particular, the value of the radius R_g of said circular groove (i.e. the distance between the middle of the circular groove and the rotation axis of the roller when the adaptive ring is mounted on said roller) is comprised between the value of the inner radius and the outer radius of the adaptive ring, and equals to the radius R of the maintaining ring 6. The outer radius of the adaptive ring is the distance between the rotation axis B and the outer surface of the adaptive ring, i.e. which is the farthest from the rotation axis B, and the inner radius of the adaptive ring is the distance between said rotation axis B and the inner surface of the adaptive ring, which is the closest to the rotation axis B. Preferentially, said flange 51 or protuberance of the bearing assembly 5 also comprises a circular groove for receiving said maintaining ring 6, wherein the radius of the flange 51/ protuberance circular groove equals to the radius of the circular groove of the side of the extreme adaptive ring 11A which is facing said flange 51 / protuberance. In particular, all above-mentioned circular grooves have the same radius. Preferentially, the radius of said circular grooves and of said maintaining rings 6 is close or equal to the radius of the annulus shape side surface.

[0016] In particular, each circular groove is configured for receiving a maintaining ring 6. The succession of adaptive rings 11 according to the invention, as well as the roller 1 or bearing assembly 5, are configured so that when the adaptive rings 11 are mounted on the roller, e.g. on the bearing assembly 5 of said roller 1, each circular groove is facing another circular groove of same radius, so that one maintaining ring 6 is fitted together into two circular grooves. The maintaining rings 6 are therefore mounted into said circular grooves between the successive adaptive rings 11, and into said circular grooves between the extreme adaptive rings 11A and the bearing assembly 5, e.g. between the extreme adaptive ring 11A and the flange 51 or protuberance of said bearing assembly that comprises also a circular groove. Advantageously, placing maintaining rings 6 between each adaptive rings 11 and between the extreme adaptive rings 11A and the flange 51 or protuberance they are facing prevents filthy infiltration and at the same time grants the needed strength required during the pinching process. In particular, the sum of the depths of two circular grooves facing each other is at least equal to the width of the maintaining ring 6 that is configured for being fitted into said facing circular grooves. Preferentially, the depth of each circular groove is equal to half the width of the maintaining ring 6, and each maintaining ring 6 according to the invention has the same width. The cooperation of the maintaining rings 6 with the circular grooves allows to distribute the gap A between the adaptive rings 11 between the two flanges 51 or protuberances serving as lateral support.

[0017] According to another preferred embodiment, each adaptive ring 11 comprises a plurality of longitudinal holes (i.e. each hole is parallel to the rotation axis B of the adaptive ring 11) designed for receiving said maintaining rods, wherein said holes are disposed in such a way that once the adaptive rings are mounted side by side on the roller, preferentially between the flanges 51 or protuberances on the bearing assembly 5, each hole of each adaptive ring communicates with another hole of another of said adaptive rings so that said maintaining rod may pass into the holes through the succession of adaptive rings 11, the extremities of each maintaining rod being for example fixed to the bearing assembly 5, notably to said flanges 51 or protuberances of the bearing assembly, while keeping the above-mentioned gap A.

[0018] Preferentially, the outer surface of each adaptive ring 11 comprises a central part 111, e.g. a central circular strip, bound to the sides of the adaptive ring by joining parts 112 disposed on both sides of the central part 111. The central part 111 of the outer surface of the adaptive ring 11 is for example flat, i.e. the central circular part radial section is parallel to the rotation axis B of the adaptive ring 11, but it might also be curved (e.g. convex) or V-shaped.

[0019] Preferentially, and according to said first preferred embodiment, the surface of each joining part 112 is a conical surface that is the lateral surface of a right circular truncated cone whose generatrix are line segments directed towards the rotation axis B of the adaptive ring 11 and making an angle θ to said rotation axis B of the adaptive ring 11, wherein said angle θ equals for example 45° (i.e., the aperture of the right circular truncated cone equals 90°), whose apex would belong to said rotation axis B if the right circular cone was not truncated, and whose directrix is formed by the intersection of the central part 111 and the joining part 112. In particular, each generatrix might be then directly connected to the side surface of the adaptive ring 11, or by means of a straight line, or by means of a curve 113.

[0020] According to said first preferred embodiment, each adaptive ring 11 may move axially along said rotation axis C. Each adaptive ring 11 is therefore preferentially packed between flanges 51 or protuberances of the bearing assembly 5 while keeping a certain floating freedom that is granted by the axial distance separating said flanges 51 or protuberances and the maintaining rings 6, which might be steel rings, mounted between the adaptive rings 11. Due to this longitudinal freedom of the adaptive rings 11, any geometrical difference in the strand products 3 that are pinched together at the same time by the multi-strand pinch roll according to the invention causes an axial displacement and an adaptation of the position of the adaptive rings 11 that are in contact with said strand products 3.

[0021] According to a preferred method for pinching multi-strand products, each multi-strand product is in particular engaged in the gap or clearance between the outside surface of the upper and lower cylindrical rollers 1, 2 of the multi-strand pinch roll between two adaptive rings 11. For example, the lower cylindrical roller 2 has a shape of a cylinder with straight generatrix, and the upper cylindrical roller is a roller according to the invention, comprising therefore said adaptive rings 11. The multi-strand products 3 are in this case each engaged in a space defined by the joining parts 112 of two successive adaptive rings and the generatrix of the lower cylindrical roller. When the multi-strand pinch roll applies the pinching force on the multi-strand products 3, a reaction force F_R is generated on the adaptive rings 11 by contact of the strand product with the joining parts 112 of the adaptive ring 11, wherein the axial component F_H of this reaction force makes the adaptive rings 11 to separate, i.e. to move away from one another.

[0022] The magnitude of the axial component F_H of the reaction force F_R depends on the overall modulus of the reaction force F_R (and therefore on the pinching force) and on the shape of the adaptive ring surface in contact with the strand product 3, i.e. on the shape of said joining parts 112. In particular, if said joining part 112 has the shape of a conical surface wherein said line segments make an angle of 45° to the rotation axis C of the adaptive ring or roller, then the reaction force F_R resulting from the contact of the strand product 3 with the joining parts 112 of two neighbouring adaptive rings comprises two components:

• said axial component F_H that makes the adaptive rings separate from one another;
• a radial component F_V that compensates the radial force exerted by the roller 1 on the strand product 3.

[0023] The reaction force F_R is in particular lower in modulus than the reaction force which would be experienced by the strand product 3 when the pinch rollers have horizontal parallel surfaces contacting said strand product 3.

[0024] In particular, each generatrix of the joining part 112 is connected to the side part by a curve 113, characterized in that the angle made by the tangent at each point of said curve 113 to the rotation axis C, B of the adaptive ring 11 increases with the decrease of the curve length between said point and the side part of the adaptive ring 11. Advantageously, since said angle between the tangent and the rotation axis B, C increases with the decrease of the curve length between the tangent point and the side part of the adaptive ring 11, then the axial components F_H of the reaction force F_R resulting from a contact between the adaptive ring 11 and the strand product 3 at said tangent point also increase with the decrease of the curve length between the tangent point and the side part of the adaptive ring 11. This increase of the axial component F_H of the reaction force F_R helps the strand product 3 to penetrate between the adaptive rings 11.

[0025] Preferentially, the geometry of the outer surface of the adaptive ring 11, e.g. the length of the generatrix and the shape of the curve 113 connecting the end of a generatrix to the side of the adaptive ring, is calculated with respect to the maximum difference in the geometries, notably transverse sections or diameters, of the multi-strand products 3 after the slitting of the single cast product from which the multi-strand products 3 originate. Advantageously, said outer surface is configured so that big diameter strand products give rise to an overall axial displacement of the adaptive rings 11 in contact with said big diameter strand products smaller than the axial displacement resulting from the contact of adaptive rings 11 with a small diameter strand product.

[0026] According to a second preferred embodiment of the present invention illustrated by Figure 3, each of said adaptive rings 11 has only a radial degree of freedom and is thus only allowed to move radially compared to the rotation axis C of the shaft or roller. For this purpose, said means of coupling are in particular configured for allowing the rings to move solely in a radial direction compared to the shaft rotation axis C. Preferentially, the means of coupling are able to couple independently each adaptive ring 11 to the bearing assembly 5 of the roller 1 by mean of elastic material 75, like a vulcanize rubber, which is configured for allowing said radial displacement of the adaptive ring 11. In particular, the means of coupling 7 comprise one or more parallel keys 71 for coupling into rotation the adaptive ring 11 to the shaft 4 or its bearing assembly 5 according to the first or second preferred embodiment. In particular, the means of coupling 7 according to the second preferred embodiment comprise, for each adaptive ring, a first group of parallel keys 7 that connect the inner cylindrical surface of the adaptive ring 11 to a first cylindrical ring 72 that surrounds a second cylindrical ring of said elastic material 75, which itself surrounds a third cylindrical ring 73 configured for being connected by means of a second group of parallel keys 71 to the bearing assembly 5. Preferentially, each ring assembly comprising the adaptive ring 11 and the means of coupling 7 according to the second preferred embodiment is separated from another of said ring assembly by means of spacers 74. Preferentially, the ring assembly according to the second preferred embodiment are maintained axially by means of a pull around ring 75. Advantageously, any difference in geometry of the multi-strand products 3 may cause a radial (or vertical) displacement of the adaptive ring 11, notably by compression of the elastic material. Preferentially, the outer surface of each adaptive ring 11 is parallel to the rotation axis B, C of the adaptive ring 11 or roller 1, but might also have a v-shaped or a convex shape, wherein the distance from the centre of the outer surface to the rotation axis B is smaller than the distance between the edges of the outer surface and the rotation axis B of the adaptive ring 11 improving therefore the guidance of the strand products 3 between the upper and lower cylindrical rollers 1, 2.

[0027] Another advantage of the present invention is the equalization effect on the speed differences between the strands 3 at the contact point of the strand product with the roller of the multi-strand pinch roll. Indeed, according to material flow conservation, the sum at the exit of the slitting machine of the material flow of each strand product of said multi-strand products generated after the slitting process by separating a single cast product into said multi-strand products is equal to the material flow of said single cast product at the entrance of the slitting machine. Consequently, the bigger is the strand diameter at the exit of the slitting machine, the slower the speed and vice versa. The difference in speed between the multi-strand products is then manageable by the multi-strand pinch roll according to the invention, for example, by a multi-strand pinch roll comprising upper and lower cylindrical rollers equipped with said adaptive rings. In particular, the method according to the invention comprises an equalization of the speed v_S = Q_s/S_s of each strand product at the exit of an upstream slitting machine with the speed v_p = w·R_p of said strand product at the contact point(s) of the strand product with the adaptive ring, wherein Q_s is the flow of the strand product at the exit of the slitting machine, S_s is the section of said strand product, w is the rotation speed of the multi-strand pinch roll roller comprising the adaptive ring, and R_p is the radial distance between the contact point(s) and the rotation axis of the roller.

[0028] Indeed, due for example to the axial displacement of the adaptive rings 11 according to the first preferred embodiment, or due to the radial displacement of the adaptive ring 11 according to the second preferred embodiment, the distance R_p between the rotation axis C of the roller and the contact point(s) of the strand product 3 with the outer surface of the adaptive ring 11 varies in function of the geometry of the strand product 3. For instance, consider three strand products 3A, 3B, 3C generated from the slitting of a single cast product and having each a different diameter. The strand product 3A characterized by the bigger diameter is in contact with the adaptive ring at a contact point whose distance R_p(3A) to the rotation axis is smaller than the distance R_p(3B) to the rotation axis of the contact point of the medium diameter strand product 3B, and also smaller than the distance R_p(3C) to the rotation axis of the contact point of the smaller diameter strand product 3C. Indeed, we have: R_p(3A) < R_p(3B) < R_p(3C). The corresponding speeds at each point of contact are then V(3A) = w·R_p(3A) < V(3B) = w·R_p(3B) < V(3C) = w·R_p(3C), where w is the rotation speed of the roller. Consequently, the speed at the contact point of the strand product is adapted to the incoming flow of material engaged between the rollers of the multi-strand pinch roll according to the invention. Indeed, if at the entrance of an upstream slitting machine, the flow Q of material of the cast product is:

Q = (Section of cast product)·(cast product speed),

then said flow Q is equal to the sum of the flow q(i) of strand products i at the exit of said slitting machine, that is Q = q(3A) + q(3B) + q(3C) = S(3A)·V(3A) + S(3B)·V(3B) + S(3C)·V(3C), wherein S(i) and V(i) are respectively the section and the speed of the strand product i at the exit of the slitting machine, with i = 3A, 3B, 3C, and wherein the speed V(i) of the strand product depends on the size of its section S(i), the speed of the strand products at the exit of the slitting machine being only equal if their sections are also equal. And therefore, the speed of each strand product V(i) in the multi-strand pinch roll according to the invention will depend on the size of its section, wherein the speed V(i) of said strand product is in particular inversely proportional to the value of its diameter.

[0029] Finally, a same roller might be equipped with different sets of adaptive rings, wherein each set of adaptive rings is chosen in function of the size and / or shape of the strand products to pinch and adapted to the geometry of said strand products.

[0030] In summary, the present invention discloses a multi-strand pinch roll and a pinching method in particular carried out by means of said multi-strand pinch roll which have as main advantages compared to prior art techniques the adaptive capacity of the rings and the equalization effect in terms of pinching pressure and peripheral speed.

Claims

1. Multi-strand pinch roll comprising an upper roller (1) and a lower roller (2) configured for pinching multi-strand products (3), characterized in that at least one of said rollers (1, 2) comprises a plurality of adaptive rings (11) mounted on its outer surface, each adaptive ring (11) being designed for contacting at least one of said multi-strand products (3) during said pinching, wherein the number of said adaptive rings (11) equals at least the number of strand products (3) that have to be pinched at the same time by the multi-strand pinch roll.

2. Multi-strand pinch roll according to claim 1, wherein each adaptive ring (11) has at least one degree of freedom for adapting its position on the roller (1) it is mounted on to variations of shape in the multi-strand product (3) it is designed to contact.

3. Multi-strand pinch roll according to claim 1 or 2 wherein said adaptive rings (11) are mounted side by side on the roller (1, 2), forming therefore a succession of adaptive rings (11).

4. Multi-strand pinch roll according to one of the claims 1 to 3, characterized in that each adaptive ring (11) has solely one single degree of freedom compared to the roller, wherein said degree of freedom is provided by means of coupling configured for coupling said adaptive rings to the roller (1).

5. Multi-strand pinch roll according to one of the claims 1 to 4, characterized in that the plurality of adaptive rings (11) are coupled to a bearing assembly (5) by said means of coupling.

6. Multi-strand pinch roll according to one of the claims 1 to 5, wherein the inner surface of each adaptive ring (11) comprises a groove or a channel configured for the lubrication of the contact area of the adaptive ring (11) with the roller (1) or bearing assembly (5).

7. Multi-strand pinch roll according to one of the claims 3 to 6, wherein extreme adaptive rings (11A) of said succession of adaptive rings (11) are each laterally maintained by the bearing assembly (5) and/or the means of coupling.

8. Multi-strand pinch roll according to one of the claims 1 to 7, characterized in that said degree of freedom is a longitudinal degree of freedom.

9. Multi-strand pinch roll according to one of the claims 4 to 8, characterized in that said means of coupling are maintaining rings (6) or maintaining rods.

10. Multi-strand pinch roll according to one of the claims 7 to 9, characterized in that the adaptive rings (11) are laterally maintained by two distant flanges (51) of the bearing assembly (5), wherein the distance D separating the two distant flanges (51) each facing one of said extreme adaptive rings (11A) is greater than the sum W of the thicknesses w_i of the adaptive rings (11) forming said succession of adaptive rings (11).

11. Multi-strand pinch roll according to one of the claims 8 to 10, wherein each adaptive ring 11 comprises a circular groove designed for receiving the maintaining ring (6).

12. Multi-strand pinch roll according to one of the claims 1 to 7, characterized in that said degree of freedom is an axial degree of freedom.

13. Multi-strand pinch roll according to claim 12, wherein the means of coupling are able to couple independently each adaptive ring (11) to the bearing assembly (5) of the roller (1) by mean of elastic material configured for allowing a radial displacement of the adaptive ring (11).

14. Method for pinching multi-strand products (3) comprising the steps:

- engaging multi-strand products in a gap or clearance between the outside surface of an upper cylindrical roller (1) and the outside surface of a lower cylindrical roller (2) of a multi-strand pinch roll, wherein at least one of said cylindrical rollers (1, 2) comprises a plurality of adaptive rings (11) characterized by one degree of freedom, said adaptive rings (11) being configured for pinching the multi-strand products (3) by applying to said multi-strand products (3) a pinching force;

- for each strand product (3) of the multi-strand products that are pinched at the same time t by the multi-strand pinch roll, an automatic adaptation, according to said one degree of freedom, of a position of at least one of said adaptive rings (11) in function of the strand product section shape and size in order to equally distribute at said time t the pinching force acting on each strand product (3).

15. Method for pinching multi-strand products (3) according to claims 14, characterized in that each multi-strand product (3) is engaged in said gap or clearance between two adaptive rings (11).

Drawing