COUPLING INTERPOSED BETWEEN THE ROLLS OF A WIDENER ROLLER FOR SHEET MATERIALS

Abstract: The coupling (1) interposed between the rolls (2) of a widener roller (8) for sheet materials comprises a couple of mutually opposite ring-shaped flanges (5) having an "L"-­ shaped cross-section. Each ring-shaped flange is composed by a first metal ring (6), and a second metal ring (7). The first metal rings are bonded to the inner surfaces of the edges (14) of a couple of adjacent rolls which, together with other rolls, form the widener roller, and between the second metal rings a ring-shaped element (9) of a flexible material is interposed.

Description: The present invention relates to a coupling for connecting adjacent rolls of a widener roller for sheet material such as paper, fabrics, plastics and still other materials. Presently used widener rollers show a structure which comprises a metal shaft bent and keyed to a metal bearing frame of the machine wherein the rollers are destined to operate. On said bent shaft idle rolls are mounted, with the interposition of bearings, which are linked with one another by elastic couplings constituted by rings of a rubber material, having a diameter substantially equal to the diameter of the rolls they link together. When the widener roller operates, the rolls revolve, rigid with one another, on the shaft, and reproduce the bending thereof thanks to the elastic couplings, in which a same portion of the ring of rubber material is subject to compression stresses, when it comes to be in the concave area of the shaft, to tensile stresses when it comes to be in the convex area of the shaft, and, independently from the angular position, to shear stresses due to the rotary dragging which each roll closer to the driving side applies to the adjacent driven roll through the interposed coupling. The members which constitute the elastic couplings are therefore subjected to a plurality of stresses which are often particularly heavy, and which cause, as a consequence, the mechanical failure of the same coupings. The failure of the couplings can be also favoured by the escape of lubricant and/or by the seepage of liquids coming from the processing of the sheet material which the widener roll has to treat. From DE-A-3 311 095 there is known a coupling between rolls of a widener roller, comprising an elastic ring-shaped element interposed between two metal rings respectively secured to the tubular ends of the adjacent rolls. The elastic ring-shaped element is constrained to the two metal rings at two radial surfaces, whereas at the external peripheral surface there is no direct connection between the elastic ring-shaped element and the rolls, but a gap is provided. During the operation of the widener roller, the compressed portions of the elastic ring-shaped element can thus expand into the gap without overstressing the elastic ring-shaped element and without detrimental friction stresses on said element. In such a construction, however, the torque transmission from one roll to the adjacent one is fully entrusted to the radial surfaces of the elastic ring-shaped element and this may lead to high specific stresses on the elastic ring-shaped element in the torsional direction, so reducing its functionality over time. US-A-4 236 285 discloses a coupling having the features of the preamble of claim 1. In this coupling, the hollow is in the form of a narrow gap extending over the major part of the axial dimension of the elastic ring-shaped element and only two small portions of the peripheral surface thereof engage with the respective roll edges. From one of the flanges, pins extend axially into respective holes of the elastic ring-shaped element to ensure a torque transmission between the adjacent rolls involving a higher surface of said element. However, such an arrangement is disadvantageous in respect of axial flexibility of the element, which is low owing to the massive construction of the elastic ring-shaped element in which the rigid pins are inserted. The purpose of the present invention is to provide a couping, interposed between adjacent rolls of a widener roller, having such a structure as to provide a strong, and simultaneously flexible, link between the rolls, so as to secure the correct functionality over time of the widener roller with which said coupling is associated. Such purpose is achieved by a coupling having the features claimed in claim 1. The advantages achieved by means of the present invention essentially derive from the fact that both the stresses caused by the bending and the stresses caused by the rotary dragging, which each roll transmits to the adjacent roll through the coupling, run through an overall linking surface area which is much larger than that of the couplings known from the prior art, thanks to the division of the linking surface into two pairs of surfaces substantially perpendicular to each other in full engagement with the respective rolls, so that the value of the stresses per unit surface area is reduced with the flexibility of the coupling being increased by the "V"-shaped hollow. The present invention is now disclosed for merely exemplifying and non-limitative purposes in the figures of the hereto attached drawings. Figure 1 shows a top plan view of a widener roller equipped with couplings according to the present invention. Figure 2 shows on an enlarged scale a sectional view according to path II-II of Figure 1, of a coupling according to the present invention, mounted between two adjacent rolls on the widener roller of Figure 1. Figure 3 shows a partial sectional view of the only coupling of Figure 2 on an enlarged scale. By referring to the above figures, a coupling according to the present invention, generally indicated by the reference numeral 1 and used on a widener roller 8, comprises a pair of ring-shaped flanges 5 having an "L"-shaped cross-section, and positioned sideways and symmetrically to a ring-shaped element 9 of a flexible elastic material. Each flange 5 is formed by a first ring portion 6, and a second ring portion 7 of a metal material, positioned substantially perpendicular to each other. The first metal ring portion 6 is flat, whilst the second metal ring portion 7 is slightly concave, i.e. it is formed by two inclined sections converging towards the interior of the elastic ring-shaped element 9 with the converging point lying on a line indicated by H-H, so that together with the converging point of the second metal ring portion 7 of the second flange 5 of the pair of flanges, a restriction of the cross-section of the element 9 is defined at the line H-H, said line being substantially parallel to the portion of the axis G-G of the widener roller 8 concerned by the coupling in question, which axis G-G is neutral relatively to the bendings occurring in the coupling, as it will become more evident from the following disclosure of the operating way. The ring-shaped element 9 of flexible elastic material, is constituted by rubber caused to adhere to the second metal ring portions 7 of the flanges 5, having a smooth surface, or a surface provided with protrusions, or a toothed surface, during the step of curing or glue bonding of the same surface, so that the radial link surfaces 16 of the ring-shaped element 9 rigidly engage the second metal ring portions 7. Of the remaining surfaces of the elastic ring-shaped element 9, the surface facing the interior of the same coupling, indicated by the reference numeral 10, is flat, and the external peripheral linking surface 11 is subdivided into two surface portions 11A and 11B by a hollow 12 having a "V"-shaped cross-section with such a depth, as to come to the restriction defined at the line H-H. The surface portions 11A and 11B are inclined towards the outside of the hollow 12, in order to better adhere, during the coupling assembling step, acting as a tight-sealing gasket, to the inner, depressed surfaces 13 of the edges 14 of the adjacent rolls 2, as it is better explained in the following. The rolls 2 are mounted on a central, bent shaft 4 of the widener roller 8, and are bonded to the flanges 5 by interposing, between the surfaces of the first metal ring portions 6 and the inner, depressed surfaces 13 of the edges 14, a layer of an epoxy or cyanamide glue, or of a different glue of a similar kind. Simultaneously, the surface portions 11A and 11B of the ring-shaped element 9 are compressed and lined-up, according to a same cylindrical surface 11, so coming to adhere, and favouring the bond, due to the effect of the interposed glue, between said surface portions and the respective inner, depressed surfaces 13 of the edges 14. The adjacent rolls 2 remain separated by a small slot 15, whose axis coincides with the axis of the hollow 12. During the operation of the widener roller 8, the shaft 4 does not revolve, whilst all rolls 2 revolve around the bent shaft 4, driven to revolve by the sheet material, or by driving motor means (not shown in the figures), according to the particular form of embodiment of the widener roller, in a per se perfectly known way. During such revolution, each ring-shaped flange 5 bonded to a roll 2 tilts relatively to the ring-shaped flange 5 of the same coupling 1 associated with the roll 2 adjacent to the preceding. Each portion of the elastic element 9 is stressed by alternate bending, according to arrows "F" and "L", according to the position in which said portion comes to be relatively to the axis G-G of the widener roller 8. During the bending according to the arrows "F", the portion of ring-shaped element 9 shown in Fig. 3 results compressed (even if to only a minimum extent, due to the effect of the same hollow 12, which allows to discharge the stresses, favouring the flexibility), whilst the remaining portion of the elastic element 9, positioned at the diametrically opposite side of the coupling, results taut. The intermediate portions of material result substantially free from stresses. The same situation occurs, but with reversed stresses, in case of bending according to arrows "L". According to an alternative form of practical embodiment of the coupling 1, the flanges 5 may be also made from reinforced synthetic resins.

Claims: A coupling for connecting adjacent rolls (2) of a widener roller (8) for sheet material, comprising an elastic ring-shaped element (9) and a pair of flanges (5), said elastic ring-shaped element (9) having a peripheral linking surface (11) and two radial linking surfaces (16), said peripheral linking surface (11) being divided into a pair of surface portions (11A,11B) by an interposed peripheral hollow (12) and said surface portions being engageable with respective edges (14) of adjacent rolls (2), said radial linking surfaces (16) being engaged by said flanges (5) and said flanges (5) each having a first and a second ring portion (6 resp.7) disposed to form a substantially "L"-shaped cross section, the first portions (6) of said flanges (5) being engageable with said respective edges (14) of said adjacent rolls (2), characterised in that said hollow (12) has a "V"-shaped cross section and said second portions (7) of said flanges (5) are each formed by two inclined sections converging towards the interior of the elastic ring-shaped element (9) to define a restriction of the cross section thereof (line H-H), said peripheral surface portions (11A,11B) being inclined towards the outside in the direction of said hollow (12). A coupling according to claim 1, characterised in that the hollow (12) has a depth substantially up to said restriction (line H-H). A coupling according to claim 1, characterised in that said radial surfaces (16) are glued to said second portions (7) of said flanges (5). A coupling according to claim 1, characterised in that said radial surfaces (16) are cured to said second portions (7) of said flanges (5).

Inventors: DE LUCCHI, CESARE
Applicants: HUYCK ITALIA S.P.A.
Application year: 1988
Main classification: B65H27
IPC codes: B65H23