Pneumatically-actuated expanding shaft with mechanical pre-centering means for supporting rolls and the like

Abstract: A pneumatically-actuated expanding shaft with mechanical pre-centering means for supporting rolls and the like, comprising an elongated cylindrical body (1) that can be inserted axially in a roll (20) and has, on its outer surface, multiple strips (2) which are distributed uniformly along the circumference and can expand radially by virtue of the action of pneumatic chambers (10). Furthermore, at least three of the strips (2) are elastically flexible to provide at least portions of their length that can expand radially by virtue of their intrinsic elasticity, so as to form regions for the mechanical pre-centering of the shaft with respect to the roll (20).

Description: The present invention relates to a pneumatically-actuated expanding shaft with mechanical pre-centering means for supporting rolls and the like according to the preamble of claim 1, see EP-A-0 010 266. Italian patent no. 1,217,468 in the name of the same Applicant, assumed included herein as reference, discloses an expanding shaft for supporting rolls and the like which substantially has an elongated cylindrical body provided, on its outer surface, with multiple strips that can expand radially by virtue of the action of mutually independent pneumatic chambers. In order to solve the problem of perfectly centering the shaft with respect to the core of the roll, the above mentioned patent uses mechanical pre-centering means obtained by means of a secondary axial shaft which is arranged inside the main shaft and is provided with frustum-shaped elements that engage pins that extend from the strips, so as to obtain, when the pressurized fluid is introduced, a radial expansion of the strips by mechanical action that allows to perfectly center the shaft with respect to the roll. Although this embodiment is extremely valid from a functional point of view, since it combines the advantages typical of mechanically-acting expanding shafts with the advantages of pneumatically-actuated expanding shafts, it has the drawback that it is complicated and relatively expensive to execute. A principal aim of the invention is indeed to solve the above described problem by providing a pneumatically-actuated expanding shaft with mechanical pre-centering means for supporting rolls and the like which allows to provide mechanical pre-centering of the roll without requiring greater constructive complication with respect to conventional pneumatically-actuated shafts. Within the scope of this aim, a particular object of the invention is to provide an expanding shaft in which it is possible to produce an elastic radial expansion by using directly the intrinsic elasticity characteristics of some strips, which are then kept radially expanded by pneumatic actuation. Another object of the present invention is to provide a pneumatically-actuated expanding shaft which is capable of giving the greatest assurances of reliability and safety in use by virtue of its particular constructive characteristics. Another object of the present invention is to provide an expanding shaft that can be easily obtained starting from commonly commercially available elements and materials and is furthermore competitive from a merely economical point of view. This aim, these objects, and others which will become apparent hereinafter are achieved by a pneumatically-actuated expanding shaft with mechanical pre-centering means for supporting rolls and the like, according to the invention, which comprises an elongated cylindrical body that can be inserted axially in a roll and has, on its outer surface, multiple strips which are distributed uniformly along the circumference and can expand radially by virtue of the action of pneumatic chambers, characterized in that at least three of said strips are elastically flexible to provide at least portions of their length that can expand radially by virtue of their intrinsic elasticity, so as to form regions for the mechanical pre-centering of said shaft with respect to said roll. Further characteristics and advantages will become apparent from the following detailed description of a preferred but not exclusive embodiment of a pneumatically-actuated expanding shaft with mechanical pre-centering means for supporting rolls and the like, which is illustrated only by way of non-limitative example in the accompanying drawings, wherein: figure 1 is an axial sectional view of the expanding shaft during the mechanical pre-centering step; figure 2 is a sectional view, taken along the plane II-II of figure 1; figure 3 is an axial sectional view of the expanding shaft during the pneumatic expansion of the strips; figure 4 is a sectional view, taken along the plane IV-IV of figure 3. With reference to the above figures, the pneumatically-actuated expanding shaft with mechanical pre-centering means for supporting rolls and the like, according to the invention, comprises an elongated cylindrical body, generally designated by the reference numeral 1, which has, on its outer surface, multiple strips 2 which are uniformly or non-uniformly distributed along its circumference. Three strips are provided in the illustrated example, but of course their number may be changed in any way according to the requirements, and not all the strips need have mechanical pre-centering. The strips 2 have a central portion 3 which protrudes from a base 4 which is wider so as to retain the strip inside guiding profiled elements 5 which are recessed in slots 6 provided correspondingly on the cylindrical body 1 of the shaft. The guiding profiled elements 5 are C-shaped, with outer arms 5a that engage the wings of the base 4 to prevent the radial extraction of the strips. The strips are arranged above pneumatic chambers 10 which are accommodated in the guiding profiled elements and are equipped with valves 11 that can be accessed at a distribution chamber 12 provided axially in the body 1, so that they are all mutually independent although they can all be actuated simultaneously both during the inflation of the pneumatic chambers and during their deflation. Advantageously, the pneumatic chambers are constituted by an elastically expandable tubular element, designated by the reference numeral 10a, which is separated from the strips by a band 14 and is closed and secured, at its ends, by blocks 15 which are fixed to the body. The important particularity of the invention resides in the fact that at least three of said strips 2 are elastically flexible, so as to form at least portions of their length that can expand radially by virtue of their intrinsic elasticity, so that they directly form regions for the mechanical pre-centering of the shaft with respect to the roll, which is schematically designated by the reference numeral 20. According to a preferred but not exclusive embodiment, said intrinsic elasticity is achieved by using strips 2 which have, along their longitudinal extension, a curved shape in which the convexity is directed towards the outside of the shaft, so that one of their portions, generally the central portion, is pushed elastically outwards. It should be specified that it is also possible to provide, on other strips, blocks that contrast the axial extraction of the shaft from the roll. The strips have, in their central portion 3, a recess 3a which runs longitudinally and has the purpose of allowing to insert square steel bars to provide better engagement, especially with steel cores. Advantageously, it is also possible to use, instead of a single strip that affects the entire length of the shaft, multiple strips which are arranged one after the other and are all curved so as to have a portion that is pushed elastically outwards and allows to mechanically pre-center the shaft with respect to the roll, designated by the reference numeral 20. As shown schematically in the drawings, in the initial step it is possible to insert the cylindrical body 1 inside the roll 20, achieving mechanical pre-centering, by using the intrinsic elasticity of the strips. Once mechanical pre-centering has been performed, pressurized fluid is introduced in the chambers 10, accordingly causing the uniform radial expansion of the entire strip or of all the strips along the length of the shaft, thus achieving firm support of the roll with respect to the shaft. From the above description it is thus evident that the invention achieves the intended aim and objects, and in particular the fact is stressed that a shaft is provided in which the mechanical pre-centering means do not require an independent actuation of their own but are obtained by directly using an elastic deformation of the strips which, in the absence of stresses, have a curved shape with a central portion that is pushed elastically outwards and which, in the presence of the pneumatic pushing action applied by the chambers, arrange themselves in extracted position along their entire length, so as to accordingly adhere perfectly to, and lock on, the roll 20. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims: Pneumatically-actuated expanding shaft with mechanical pre-centering means for supporting rolls (20) and the like, comprising an elongated cylindrical body (1) that can be inserted axially in a roll (20) and has, on its outer surface, multiple strips (2) which are distributed uniformly along the circumference and can expand radially by virtue of the action of pneumatic chambers (10), characterized in that at least three of said strips (2) are elastically flexible to provide at least portions of their length that can expand radially by virtue of their intrinsic elasticity, so as to form regions for the mechanical pre-centering of said shaft with respect to said roll (20). Expanding shaft according to claim 1, characterized in that said at least three strips (2) have, in transverse cross-section, a central portion (3) that protrudes from a wider base (4) accommodated inside guiding profiled elements (5) which are recessed in slots formed correspondingly on said cylindrical body, said guiding profiled elements (5) being C-shaped, with outer arms (5a) that can be engaged by the edges of said wider base (4). Expanding shaft according to the preceding claims, characterized in that said strips (2) are arranged above said pneumatic chambers (10) each being constituted by an elastically expandable tubular element (10a) with the interposition of a band (14). Expanding shaft according to one or more of the preceding claims, characterized in that each one of said tubular elements (10a) that constitute said pneumatic chambers (10) is provided with a valve (11) that is arranged at a distribution chamber (12) which is provided axially in said body (1) for the simultaneous actuation of the valves (11) both during the inflation of said pneumatic chambers (10) and during their deflation. Expanding shaft according to one or more of the preceding claims, characterized in that the intrinsic elasticity of said strips (2) is produced by a shape which curves along their length and in which the concavity is directed towards the outside of said cylindrical body (1). Expanding shaft according to one or more of the preceding claims, characterized in that it comprises multiple strips (2) which are arranged one after the other, each one of said strips (2) having a curved shape in which the convexity is directed towards the outside of said cylindrical body (1). Expanding shaft according to one or more of the preceding claims, characterized in that said strips (2) have, at one of their central portions (3), a recess (3a) that runs longitudinally.

Inventors: GATTRUGERI GIOVANNI, GATTRUGERI, GIOVANNI
Applicants: IES SRL, I.E.S. INTERNATIONAL EXPANDING SHAFTS S.R.L.
Application year: 1995
Main classification: B65H75
IPC codes: B65H75