WO1995034689A1

WO1995034689A1 - Rotary body suspension device

Info

Publication number: WO1995034689A1
Application number: PCT/EP1995/001717
Authority: WO
Inventors: Emile Lonardi; Giovanni Cimenti
Original assignee: Paul Wurth S.A.
Priority date: 1994-06-14
Filing date: 1995-05-05
Publication date: 1995-12-21
Also published as: CN1042648C; AU2525995A; BR9507419A; CZ365696A3; EP0765404B1; LU88495A1; DE69501894D1; CZ284396B6; JPH10501304A; EP0765404A1; DE69501894T2; CN1149320A

Abstract

A suspension device for rotary bodies such as rotary hoppers has on one side a metal bearing band which defines a ring-shaped rolling surface (34) and on the other side at least n metal rollers (24), n being an integer higher than 3. The n rollers (24) contact said rolling surface (34). An elastic compressible member (32), preferably a metal web provided with oblong holes (40) parallel to the rolling surface (34), is arranged below the metal bearing band so that the rolling surface is elastically deformed around the contact points (Pi) between the rollers (24) and the rolling surface (34). These elastically compressible members (32) are sized so that the elastic deformation of the rolling surface (34) is sufficient to substantially correct an unequal distribution of the weight of the rotary hopper (14) on the n rollers (24) due to slight surface irregularities of the n rollers (24).

Description

SUSPENSION DEVICE FOR A ROTATING BODY

The invention relates to a suspension device for a heavy body rotating around a substantially vertical axis, such as for example a rotary hopper. It relates more particularly to a device of this kind which comprises, on one side, a metal tread defining an annular rolling surface and, on the other side, at least n rollers, or n is an integer greater than 3 , these n rollers being arranged so as to bear on said rolling surface to support said body in rotation.

A device of this kind is for example known from the document US-A-4,812,100, in which it is described in relation to a rotary hopper of a shaft furnace. Such a rotary hopper weighs, when loaded, several hundred tonnes. If we were working with three support rollers spaced 120 ° apart, each roller should be sized to take at least a third of the weight of the hopper. However, it is naturally beneficial to work with rollers as small as possible. Hence the idea of working with more than three pebbles. But this idea poses problems with regard to its practical implementation. Indeed, if we analyze the case where the hopper is supported by four rollers spaced at 90 °, we realize that instead of being able to size each roller to take up 25% of the weight of the hopper, we must size each roller be able to take back at least 50% of the weight of the hopper. This paradox is due to the fact that the four rollers are indeed never strictly aligned in the same plane.

In the aforementioned document, the problem of distributing the weight of the hopper over more than three rollers has been resolved by providing four pairs of rollers provided with a special suspension. The rollers of a pair are indeed carried by an axle that can pivot around a radial axis and each of the rollers is mounted in its axle using floating bearings fitted with springs.

The problem underlying the present invention is to provide a device of the type described in the preamble which is much simpler than the device described in document US-A-4,812,100 and which is nevertheless capable of substantially correcting an uneven distribution of the weight of said heavy body on more than three rollers.

According to the present invention this problem is solved by elastically compressible means which are arranged below the tread so that the tread surface has elastic deformations around the points of contact between the rollers and the surface of the tread. rolling. These elastically compressible means are on the other hand dimensioned so that said elastic deformations of the rolling surface are sufficient to substantially correct an uneven distribution of the weight of said heavy body on the rollers resulting from slight defects in co-planarity of the rollers.

The present invention has the advantage that the suspension of the n rollers can be much simpler than that described in document US-A-4,812,100 while guaranteeing sufficient results from the point of view of load distribution between the n rollers. Said elastically compressible means could of course be a ring of elastomeric material which is arranged below the metal tread which defines the rolling surface. It will however be appreciated that the present invention provides elastically compressible means which are entirely metallic. According to a preferred embodiment of the invention, these elastically compressible means indeed comprise a metal strip provided with oblong holes parallel to the rolling surface. It will be appreciated that this is a particularly simple solution to perform, which costs almost nothing, which requires no maintenance and which has excellent characteristics from the point of view of elastic deformations.

The device according to the invention advantageously comprises a support cylinder which is coaxial with the axis of rotation and has a high rigidity, a

^Annular mounting flange supported by a first end of said support cylinder and a tread secured to said support flange. The support cylinder then has, near the fixing flange, oblong holes parallel to the running surface. When this solution is applied to a rotary hopper, said support cylinder forms for example the cylindrical wall of the hopper. It will also be noted that the raceway can be either integral with the rotating body, or be integral with the support structure.

Other advantages and characteristics of the invention will be deduced from the detailed description of a preferred embodiment of the invention, applied by way of example to a rotary hopper of a blast furnace, and from the drawings below. attached, in which: - Figure 1 is an elevation of a blast furnace equipped with a rotary hopper provided with a suspension device according to the invention; - Figures 2 and 3 serve to illustrate the problem underlying the invention; they show in a plan view a device with three support rollers (Figure 2); respectively four support rollers (Figure 3);

- Figures 4A and 4B are linear developments of a suspension system with four rollers; the system of Figure 4B shows the system of Figure 4A after it has been made according to the invention;

- Figure 5 is a section through a vertical plane through the suspension device according to the invention of the rotary hopper of Figure 1;

- Figure 6 is used to schematically explain using two diagrams the deformations of the rolling surface in a preferred embodiment of the device according to the invention.

Figure 1 shows the upper part of a blast furnace 10 equipped with a loading device 12 with central supply. This loading device 12 comprises in particular a holding hopper generally identified by the reference 14. It is a rotary hopper which can rotate around the central axis 16 of the blast furnace 10, in order to avoid an asymmetrical supply. a lock hopper 15 located below the holding hopper 14.

The holding hopper 14 is installed on a platform 18 which is in turn supported by a superstructure 20. The latter is supported on the wall 20 of the blast furnace 10. The suspension of the hopper 14 on the platform 18 is produced using four rollers 24 mounted on the platform 18. These rollers 24 bear on an annular tread 26 which surrounds the hopper 14 and is integral with the latter.

In FIG. 1, it can also be seen that the hopper 14 comprises an upper part, which comprises a cylindrical wall 28, and a lower part, which comprises a frustoconical wall 30. The tread 26 is fixed to the lower edge of the cylindrical wall 28 This edge protrudes slightly downward relative to the joint between the cylindrical wall 28 and the frustoconical wall 30. Such a hopper 14 of a loading installation 12 of a blast furnace 10 weighs, when loaded, several hundred tonnes. This weight must be taken up by the support rollers 24 to be transmitted through the platform 18 and the superstructure 20 on the wall 22 of the blast furnace 10.

The problem underlying the present invention will be discussed with reference to Figures 2, 3 and 4A. In Figure 2 we see three support rollers spaced 120 ° apart. The axes of rotation of the three rollers have a point of intersection on the axis 16. It is obvious that in this arrangement the three rollers 24- | , 242 and 243 each support one third of the total weight of the hopper 14, when the center of gravity of the hopper is located on the axis 16. At first sight it would therefore be assumed that in the case of Figure 3 each of the four rollers 24-j, 242, 243 and 244 would have to support a quarter of the total weight. In practice, however, this is not the case. Indeed the four points P- _| , P2, P3 and P4 of the rollers 24, which represent the potential points of contact of the rollers 24-j, 242, ² ^ 3 ^{and 24} 4 ^with ^a rolling bar 26, are never strictly situated in the same plane. As a result, the raceway bears only on three rollers. In FIG. 4A, which is a linear development of the device in FIG. 3, it is the rollers 24y, 243 and 244 which are in contact with the raceway. In Figure 3 we see that the projection G of the center of gravity of the hopper 14 is located on the half-line [0, P4 [at a distance "e" from point 0. It is then easy to verify that the reactions to the rollers are the following: R ₂ = 0; R = (2e / D) ^* P; R ₁ = R ₃ = (P / 2) ^* (1 - e / D) where D is the diameter of the rolling circle 32.

However, the ratio (e / D) is generally very small (in other words, the eccentricity of the center of gravity G of the hopper 14 is low), which means that each of the four rollers should be sized to take up 50 % of the weight of the hopper. It is also important to note that the tread 26, which is fixed to the lower front surface of the cylinder 28 with a vertical axis, can be likened to the sole of an almost infinitely rigid beam. In other words, the tread 26 has almost no deformation. In Figure 4B we see the four-roller suspension device of the

Figure 4A which has been modified in accordance with the invention. It will be noted that the tread 26 has been mounted on an elastically compressible element 32 so that the tread surface 34 of the tread 26 can now have elastic deformations locally around the contact points Pj between rollers 24j and tread surface 26. The tread 26 / elastically compressible element 32 assembly has been dimensioned more specifically so that these local elastic deformations of the tread surface 34 at the location of the rollers 24j are sufficient to substantially correct an uneven distribution. the weight of the hopper 14 on the four rollers 24j. Following these pre-programmed local deformations, the running surface 34 has given way under the rollers 24 <| and 243 where, in Figure 4A, the reactions Rj and R3 each represented approximately 50% of the total weight of the hopper 14. Due to these local deformations on the rollers 24 <| and 243_ the wall 28 has slightly collapsed. The roller 242 is now in contact with the running surface 34. At the same time there has been a notable redistribution of the weight of the hopper between the four rollers. In other words, the element 32 gives the metal tread 26 an elastic capacity sufficient to correct the effect of the co-flatness defects of the four rollers 24j by local deformations and thus obtain a better distribution of the weight of the hopper 14 on the four rollers 24j. Figure 6 shows an element of the compressible band 32 interposed between the tread 26 and the cylindrical wall 28 almost infinitely rigid. It can be seen that the compressibility of the strip 32 is obtained in a clever way, by simply providing the cylindrical wall 28, near the tread 26, with oblong holes 40 which are parallel to the rolling surface 34. These holes 40 are distributed in the wall 28 with a symmetry of revolution, preferably in two superimposed rows. It will be noted that the oblong holes 40 in the upper row are offset with respect to the holes in the lower row so that they cover the material between two successive holes in the lower row. The effect of this particular arrangement of the oblong holes 40 will be studied using diagrams A and B in FIG. 4.

In these two diagrams A and B of Figure 4 the element 32 is modeled by two ideal beams 34 'and 42' which are superimposed. The beam 34 'models, from the deformation point of view, the rolling surface 34. The beam 42' models, from the deformation point of view, a fiber 42 'located between the two rows of oblong holes 40. The beam 34' is supported on the beam 42 'using elastic supports 44. The latter represent the spaces (that is to say the material of the wall) between the holes 40 of the lower row. These spaces are overhung by the holes 40 of the upper row and are therefore elastically deformable in the direction of these oblong holes. The beam 42 'is supported on rigid supports 46. The latter represent the material of the wall 28 overhanging the holes 40 of the lower row.

Diagram A presents the two virtual beams 34 'and 42' in the non-deformed state (reaction R = 0). Diagram B represents the deformations of the two virtual beams 34 'and 42' when a large point load ^R MAX ^is applied to the beam 34 'directly above the first rigid support 46. It it is noted that between the supports 44 the beam 34 'deforms freely due to the presence of the hole 40 of the first row. The rigid support 46 which models the almost infinitely rigid wall 28 above this hole has practically no influence on this deformation. In addition, the elastic supports 44 yield elastically under the load R due to the holes 40 in the upper row. The sum of these two deformations represents the local deformation of the rolling surface at the point of contact Pj of the point force R. It will be noted that mathematical models of this structure with oblong holes, using for example finite elements, have made it possible to find that local elastic deformations of the rolling surface 32 can be achieved, which are, in the case of concrete applications, far enough to significantly influence the distribution of the weight on the rollers, when a hopper of the kind described above is supported by more than three rollers. These mathematical models of the structure with all oblongs have also made it possible to draw certain conclusions as to the dimensioning of the oblong holes 40. Taking into account practical constraints related to the realization of oblong holes, we can summarize these conclusions as follows:

- shape of the holes: rectangular with rounded ends;

- dimensions of the holes: the length of a hole preferably corresponds to that of an arc of a circle with an angle of less than 10 °; the height of a hole corresponds to about a quarter of its length;

- hole arrangement: two rows of superimposed holes; the length of the space between two successive holes in a row represents approximately 80% of the length of the holes; a hole in the second row is symmetrical with respect to the plane of symmetry of two holes in the first row.

Those skilled in the art will be perfectly capable of optimizing, respectively adapting these parameters for each application case, for example by using a finite element program to model the particular application case. Other important characteristics of the proposed device will be described with the help of Figure 5, which shows in a section an enlargement of the location of the hopper 14 which is surrounded by a circle in Figure 1. We see that annular fixing flange 50 is fixed by welding to the deformable element 32. The tread 26 is screwed onto this fixing flange 50. It is moreover advantageously divided into five annular sectors of 72 ° each. Thus, there are never two rollers which rest on the same tread sector, nor two rollers which are located on a joint between two of these sectors. This segmentation of the tread 26 into n + 1 segments therefore has a favorable influence on the "penetration" of the reactions of the rollers in the rolling surface 34. A circumferential nesting 52 moreover ensures easy and adequate positioning of the different segments of the tread on the flange 50. These segments can in fact be considered as wearing parts which must be replaced regularly. The tread 26 defines a conical tread surface 34. The top of the cone which generates this surface is located below the tread surface on the axis of rotation 16. It will also be noted that the tread 26 has advantageously a hollow section. The rolling surface of the rollers 24 is curved so as to ensure almost point contact of the rollers 24 with the conical rolling surface 34 along a contact circumference. In order to ensure optimum recovery of forces by the deformable element 32, this contact circumference merges with the projection of the center line of the cross section of the cylinder 28 on the rolling surface.

Those skilled in the art will readily apply the teaching of the present invention to more than four rollers. In a device of the kind of that of Figure 1 we will preferably work with four pairs of rollers spaced 90 °. On the platform 18 these pairs of rollers are then mounted at the four most rigid locations on the platform 18, that is to say at the connecting nodes between the platform 18 and the superstructure 20.

The suspension device according to the invention has been described above with reference to a rotary hopper. It could however be applied to other heavy bodies rotating around an axis (for example a tank, a rotary loading chute, a rotating platform etc.) when it is a question of using more than three support rollers to reduce the load per roller.

Claims

1. Suspension device for a heavy body rotating around a substantially vertical axis of rotation (16), in particular a rotary hopper (14), comprising on one side a metal tread (26) defining an annular rolling surface (34) and on the other side at least n metal rollers (24), where n is an integer larger than three, these n rollers (24) being arranged to bear on said rolling surface (34) to supporting said rotating body (14) about said substantially vertical axis of rotation (16), characterized in that elastically compressible means (32) are arranged below the metal tread (26) so that the surface of bearing has elastic deformations around the contact points (P _j ) between the rollers (24) and the rolling surface (34), said elastically compressible means (32) being dimensioned so that said elastic deformations are sufficient to substantially correct an uneven distribution of the weight of said heavy body (14) on said rollers (24) resulting from slight defects in co-flatness of the n rollers (24).

2. Device according to claim 1, characterized in that said elastically compressible means comprise a metal strip (32) provided with oblong holes (40) parallel to the rolling surface (34).

3. Device according to claim 1, characterized by a support cylinder (28) which is coaxial with the axis of rotation and has a high rigidity, an annular fixing flange (50) supported by a first end of said support cylinder ( 28), a tread (26) fixed to said support flange (50), said support cylinder (28) having, near the fixing flange (50), oblong holes (40) parallel to the rolling surface (34).

4. Device according to claim 2 or 3, characterized by at least two rows of oblong holes (40) parallel to the rolling surface (34), the holes of the first row being offset from those of the second row.

5. Device according to claim 4, characterized in that the holes of the second row overhang the spaces between the holes of the first row.

6. Device according to any one of claims 2 to 5, characterized in that the length of the oblong holes (40) is less than 10 °.

7. Device according to any one of claims 2 to 6, characterized in that the ends of the oblong holes (40) are rounded.

8. Device according to any one of claims 2 to 7, characterized in that the arrangement of the oblong holes (40) has a symmetry of revolution around the axis of rotation (16).

9. Device according to any one of claims 3 to 8 characterized in that the tread (26) has a hollow section.

10. Device according to any one of claims 3 to 9, characterized in that the tread (26) is segmented into n + 1 annular segments.

11. Device according to any one of claims 3 to 10, characterized in that the contact circumference between the tread (26) and the rollers (24) corresponds to the projection of the cross section of said support cylinder.

12. Device according to any one of claims 1 to 11, characterized in that the rolling surface (34) is a conical surface, the top of the cone generating this surface being located on the axis of rotation, and in that the rolling rollers (24) have a convexly curved rolling surface (34).

13. Device according to any one of claims 1 to 12, characterized in that the raceway (34) is integral with the rotating body (14), and in that the rollers (24) are rigidly fixed on a flat - support form (18).