SHOULDER FOR ROLLING MILL STAND WITH OPEN-TYPE UPRIGHTS

Abstract: A shoulder structure for rolling mill stand is described, whose uprights are of open type, being formed of two wings (3A, 3B), respectively inner and outer wing, preferably independent from each other or connected through either a web (3C) in the middle zone only or by means of cross stiffening brackets. The structure of crosspieces (2) is also composed of two wings (2A, 2B), respectively inner and outer wing, which are connected through both a web (2C) extending until the beginning of the uprights (3) and a reinforcement (2D) in correspondence with the vertical symmetry axis. The shoulder in its whole may be monolithic, or obtained by casting, or assembled by welding, in which case the uprights (3) are made of rolled plates, with the connection portions (6A, 6B) between wings and crosspieces being easily accessible for welding and inspection.

Description: "SHOULDER FOR ROLLING MILL STAND WITH OPEN-TYPE UPRIGHTS" The present invention relates to stands or bearing structures of rolling mills, in particular the stand shoulders of rolling mills for steel flat products such as slabs, thin slabs and strips. The rolling stands presently known are comprised of two shoulders of elongated annular shape, each of which is usually formed as a monolithic assembly obtained by casting, wherein two uprights and two crosspieces can be seen. Therefore a shoulder of known type is characterized by simple shapes and heavy masses, such as to reach e.g. a weight in the order of 50-100 tons. The solid rectangular cross section of the uprights, if on one hand ensures a high vertical stiffness, i.e. a reduced elongation of the shoulder under load, and high horizontal rigidity, i.e. a small shrinking, under load, of the span between the uprights at the inside of which are slidably mounted the bearing-holder packings, on the other hand it has the drawback of requiring threaded, dead holes to be drilled for mounting all the apparatuses equipping the shoulder, in addition to involving the need of enclosing the upright with the cooling and lubrication pipes. Is also known that monolithic castings of so important metallic masses are sources of possible inconveniences due both to the difficulties of faultless manufacturing and to the long time of preparation. Also the solution of preparing separate castings, such as uprights and crosspieces, and then assembling the same by welding, is of difficult realization, as these weldings should be made on large cross-section areas, scarcely accessible and at a certain depth, thereby with poor guarantees of reliability for the welding itself, even in case that the uprights would be made as empty box-like elements instead of solid castings. It is therefore an object of the present invention to provide a shoulder for rolling stand which does not show the drawbacks of the prior art and in particular, although maintaining the requirements of great vertical and horizontal stiffness, comprises uprights with through openings for mounting auxiliary equipments, thus rendering available some space for various pipings, as well as for housing devices in a sheltered but accessible position, such as the usual apparatus for axially shifting the position of rollers and to feed the devices for balancing the rollers bending. All the above is obtained by means of a shoulder for rolling stand having the general features of claim 1 , namely the uprights of open-type. It should be noted that the shoulder structure according to the invention can be cast in a single piece or obtained by assembling a plurality of pieces, for example being welded to each other as it appears from the following description and the claims depending on claim 1. In the former case the casting results to be more complex as regards the shape, with respect to a conventional shoulder with solid uprights, but the portions of greatest stiffness, e.g. > 500 mm, are essentially confined to the reinforcement areas, if any, whereby the cooling occurs more quickly with consequent formation of a metallurgical shape having a finer grain showing advantages under both the aspects of the mechanical resistance, especially the resilience, and of inner defects, which are much more unlikely. In the case of assembled, in practice welded shoulder, it will be possible to use for the wings of both uprights, thick plates or however rolled products having metallurgical and mechanical features certainly better than a casting product, while also the crosspieces can show superior qualities as the relevant casting is of reduced volume. Furthermore the welding between the uprights wings and the crosspiece can be performed in an area of easy access and inspection, thus resulting to be more reliable. In this case the maximum weight of casting to be obtained is restricted to less than 35% of the total weight of the shoulder and this feature makes the shoulder itself to be ready more quickly, since the present limits of time, which are one of the greatest drawbacks of the known monolithic structures, essentially depend on the casting weight. Finally not the last advantage of a composable shoulder is given by the fact that the stand height can be modified even after the supply of the two cast crosspieces: it will be sufficient to cut at the required size the thick plates available e.g. in stock. This and additional objects, advantages and features of the stand shoulder for rolling mill according to the present invention will appear more clearly from the following detailed description of some preferred embodiments thereof, given by way of non-limiting example with reference to the annexed drawings in which: Figure 1 shows a perspective view of a first embodiment of the shoulder according to the invention having the uprights wings free; Figures 2 and 2a shows respectively a front view and a side view of the same shoulder of figure 1, with said wings being connected through a web in the central portion; and Figure 3 shows a perspective view of a further embodiment of the shoulder according to the invention. With reference to the drawings, where the same numeral references correspond to equal or similar members, the structure of uprights 3, according to the present invention comprises for each upright an inner wing 3A and an outer wing 3B which in the embodiment of Figures 2 and 2a are connected to each other in the central portion only through to a web 3C, whereas in the embodiment of Figure 1 and 3 they are independent from each other. It should be noted that instead of the web 3C there could be provided stiffening cross brackets (not shown) for joining both wings of the upright. Also the crosspieces 2 comprise an inner web 2A and an outer web 2B with a reinforcement 2D in correspondence with the vertical symmetry axis. Such a reinforcement has the function of distributing the forces exerted onto the zone of the inner wing 2A and deriving from the action of the mechanical or hydraulic means intermediate between the bearing-holders packings (not shown) and the shoulder itself. The action of the separating force Fs acting onto 2A leads to a situation of tension in the wings of both uprights, which is due both to a pull along a single axis and to the fixing moment between uprights and cross piece. The two actions add the to each other on the inner upright 3A, whereas on the outer one 3B the bending is deducted from the strain status generated by the pull along one single axis. Therefore, the inner upright 3A will have preferably a cross-section area larger than that of upright 3B. Furthermore in case there is no web 3C or any possible other connection between the two wings of uprights 3, like in the embodiments of figures 1 and 3, the horizontal shift or bending of wing 3A towards its corresponding one at the opposite side of the shoulder is lower than the shift of the outer wing 3B to the same direction. The advantage is thereby obtained that the closing effect of the window or port 4 as defined by the inner wings 3A is reduced with respect to the similar effect in a conventional stand of the same weight. In fact with the structure according to the present invention the theoretical assumption of a hinge between crosspiece and uprights is better approached, thus reducing the extra-stresses due to the fixed-end junction. Furthermore it could be appreciated that while the vertical deformation can be easily balanced through the well known devices for controlling the position of the rollers, such as hydraulic capsules, the closure of the port between uprights can be taken into account only in calculating the gaps between slide plate or guides 5 and bearing packings. Therefore the shoulder according to the invention allows to operate with lower plays between bearing-holder packings and guides 5, with a multiplicity of operational advantages such as the reduction of possible instability phenomena in the bearing packings, or by keeping under control the conditions of the packings themselves sliding under load along the guides 5. Finally it is noted that, although 6A and 6B are a representation of the welding lines between the crosspieces 2 and the inner and outer uprights 3A and 3B, respectively, the shoulder can be made as a monolithic casting, so as to provide in any case advantages with respect to the conventional solid structure. In fact the thickness will be substantially reduced except for the possible reinforcement area 2D, which however dan be formed as in the solution of figure 3, that it is with opening, thereby still lightened. In case of a structure being assembled by welding, the advantages of this solution have been already listed before and it is clearly seen in the drawings that the wings 3A, 3B are fully accessible in the areas 6A, 6B, both in the embodiment of figures 2, 2a with the web 3C, due to the presence of openings 7 in the connecting areas with the crosspieces 2, and even more in the embodiments of figures 1 , 3 where there is provided no intermediate web. Since the wings 3A, 3B have preferably a thickness lower than 400 mm and are accessible from both sides, the welding can be carried out with a depth of less than 200 mm from the surface, with clear advantages, already pointed out with respect to a possible welding between solid elements or a solid one and a box-shaped closed element. The wings of the uprights are preferably formed of rolled sheets or plates, which can be easily supplied and are possibly available in stock for being cut at a given size even after the crosspieces are made ready. Possible additions and/or modifications can be introduced by those skilled in the art to the above-described and illustrated embodiments of the rolling mill stand shoulder according to the present invention without exceeding the scope of the invention itself.

Claims: CLAIMS 1. Stand shoulder structure of rolling mill for steel flat products, of elongated annular shape being comprised of two cross-pieces (2), lower and upper ones, and two side uprights (3), characterized in that said uprights (3) are of open type, as each of them is formed of an inner wing (3A) and an outer wing (3B) essentially parallel to each other and also said crosspieces (2) are each composed of two wings (2A, 2B), inner and outer respectively, which are connected to each other through a web (20) extending to the beginning of the uprights (3), with a reinforcement (2D) in correspondence of a vertical symmetry axis. 2. A structure according to claim 1, characterized in that the inner wing (3A) of each upright (3) has a cross-sectional area larger than that of said outer wing (3B). 3. A structure according to claim 1 or 2 characterized in that said both inner (3A) and outer (3B) wings of the uprights are connected to each other, in the middle portion of their height, through a web (30) of reduced thickness, with an opening (7) towards the crosspieces (2). 4. A structure according to claim 1 , characterized in that each crosspiece (2) is a separate casting whose inner (2A) and outer (2B) wings are welded respectively to the inner (3A) and outer (3B) wings of the side uprights along respective welding lines (6A, 6B). 5. A structure according to claim 4, characterized in that both wings (3A, 3B,) of each upright (3) are formed of thick plates parallel and spaced apart from each other. 6. A structure according to claim 5, characterized in that the two plates forming the wings of uprights (3) are connected to each other through a web (30) in the central zone only, while leaving opening (7) at the ends. 7. A structure according to claim 5, characterized in that said plates forming the wings of uprights (3) are connected to each other by means of cross stiffening brackets. 8. A structure according to claim 4, characterized in that the junction between the crosspieces (2) and inner wings (3A) of the uprights has a static behaviour approaching that of a hinge. 9. A structure according to any one of the claims 1-3, characterized by the fact of being monolithic, obtained by casting.

Inventors: CATTANEO FILIPPO, ROSSI ANTONINO, CATTANEO, FILIPPO, ROSSI, ANTONINO
Applicants: CATTANEO FILIPPO, INNOCENTI ENG SPA, ROSSI ANTONINO, CATTANEO, FILIPPO, INNSE INNOCENTI ENGINEERING S.P.A., ROSSI, ANTONINO
Application year: 1996
Main classification: B21B31
IPC codes: B21B31