Abstract:
Braking roller for systems for cutting metal bands into strips, characterized in that it comprises a rotating and motorized ( 21 ) shaft ( 20 ), with two supported (in  33 ) end pins ( 22, 23 ), which in a central side surface ( 24 ) carries a series of idle pulleys ( 25 ), axially held (in  27 ), in said central side surface ( 24 ) there being provided at least one recess ( 30 ) inside which there is arranged at least one inflatable element ( 29 ) above which there is arranged at least one wear element ( 34 ) that is made to abut inwards of each idle pulley ( 25 ). The roller can be used both into a tow group and as braking bridle or as baffle roller according to the specific need.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a braking roller for systems for cutting metal bands into strips. 
     There are known systems that carry out the longitudinal cutting of metal bands into a series of longitudinal strips that are afterward used for various transformations. 
     In these systems for the longitudinal cutting of metal bands into strips, which are more commonly known as “slitters”, it is essential that once cut, the strips obtained from the band correctly wind so as to prevent difficulties of both rewinding and of successive treatment. 
     For this purpose, a braking system of the same strips is provided before their winding into single rolls. 
     The braking system that is part of the system itself must guarantee a correct and even winding tension of the single strips. In fact, it must be possible to compensate the difference of speed that generates after possible differences of thickness between a strip and the other, since the transversal section of the initial band may not have an even thickness. In fact, it may be thinner at the longitudinal side edges with central swelling, or it may be thinner centrally starting from the thicker longitudinal edges. 
     Moreover, these differences of speed and optional braking systems must not damage the surface of the band being machined, that must be protected as much as possible. 
     For example, felt elements used as braking system are known, guided into containment housings, that are determined in engagement on the strips of the passing band through an underlying inflatable thrust element. Since such elements transversally arranged with respect to the band, or to the single strips, are standstill with respect to the band, they cause a rapid wear and in any case, they do not guarantee the respect of the band surface. 
     As an alternative, the rubber surface of braking rollers—called “presser rollers”—acting on the band strips, has also been provided with a series of surface peripheral notches, transversal to the roller axis, thus creating a series of rubber teeth that may allow some possibilities of bending in the advancement direction of the strip, or in the opposite direction. Such “folding” or “yielding” surface tooth should facilitate the adaptation to the speed of the single strip of the braking roller. In this way, there would be a suitable differentiated braking on the associated strips cut from the band. 
     Also this solution exhibits some limitations due to the minimum quantity of deformation that is possible to obtain due to the operation noise and to the regulation difficulties. 
     SUMMARY OF THE INVENTION 
     Purpose of the present invention is therefore that of realising a braking roller, called “presser roller”, for systems for cutting metal bands into strips, which should solve the above technical problems. 
     Another purpose is that of eliminating any possible difficulty of braking even in the presence of strong variations between the speeds of the different strips obtained from the cutting. 
     Another purpose is that of eliminating any possible defect that may arise on the surface of the strips due to the braking, so as to protect the surfaces of the same strips. 
     Another purpose is that of realising a braking roller for systems for cutting metal bands into strips that should be little expensive and easy to manufacture and operate, without problems of continuous adjustment or setting interventions. 
     These purposes according to the present invention are obtained by realizing a braking roller for systems for cutting metal bands into strips, comprising a rotating and motorized ( 21 ) shaft ( 20 ), with two support bearings ( 33 ) adapted to support end pins ( 22 ,  23 ), which are located within a central side surface ( 24 ), which carries a series of idle pulleys ( 25 ), axially held by two side containment flanges ( 27 ), wherein said central side surface ( 24 ) there is provided at least one recess ( 30 ) inside which there is arranged at least one inflatable element ( 29 ) above which there is arranged at least one wear element ( 34 ) that is made to abut inwards of each idle pulley ( 25 ). 
     Additional features are illustrated in the dependent claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and advantages of a braking roller for systems for cutting metal bands into strips according to the present invention will appear more clearly from the following exemplificative and non-limiting description, made with reference to the attached schematic drawings. In such drawings: 
     FIG. 1 shows a perspective view of a first embodiment of a system for cutting a metal band into a series of strips wherein at least one braking roller according to the present invention is used; 
     FIG. 2 shows a perspective view of a second embodiment of a system for cutting a metal band into a series of strips wherein at least one braking roller according to the present invention is used; 
     FIG. 3 shows a front partly sectioned view of a braking roller according to the present invention; 
     FIG. 4 shows an enlarged transversal section of the braking roller of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to FIGS. 1 and 2, there are shown two systems for cutting metal bands into strips, where braking rollers or “presser rollers” can be arranged according to different solutions. 
     FIG. 1 shows a system wherein a roll of band  12 , once cut through a special shear  13 , generates a certain number of strips  14 , which must then be wound into final rolls  15  through a special winding reel. Braking rollers, as well as a compensation area, are provided between shear  13  and the winding reel so as to facilitate such operation. 
     FIG. 1 shows how it is possible to provide, in the braking units, drafting elements consisting of one or two “braking rollers”, or braking rollers  16  according to the invention, in collaboration with baffle rollers  18  and simple tows  19 . FIG. 2 shows how braking rollers according to the invention can be used as baffle rollers  18  or as braking bridles  17 , thus solving the problems of known braking rollers of the prior art. 
     FIGS. 3 and 4 respectively show a front partly sectioned view of a braking roller and an enlarged transversal section of the same braking roller that in general can be used for systems for cutting metal bands into strips. 
     A braking roller  16 ,  17 ,  18  according to the present invention has been devised as braking element for “slitter” systems in general; that is to say that it can be used as component of one or more tangential braking tows, as component of one or more braking bridles, or simply as baffle roller, in the schematic system shown in FIGS. 1 and 2. 
     As it can be seen in the figures, a braking roller  16 ,  17 ,  18  consists of a series of elements combined in a particular manner. 
     In fact, a shaft  20  is provided, towed into rotation by a motor, schematised in  21 , which is thus rotating, that forms the carrying structure. Shaft  20  is provided with two end pins  22  and  23  adapted to receive support bearings, schematised in  33 , of the same roller and on one side, it connects to the above motorisation unit. 
     In general, on a central side surface  24  there is arranged a series of idle pulleys  25 , centrally drilled in  26 , arranged on the side surface  24  of shaft  20  and axially held by two side containment flanges  27 . In this way, the idle pulleys  25  can freely rotate without any axial movement, and they can be externally provided with a covering in  28 , made of a scratch-proof engagement material of various types, such as for example rubber material, leather, spunbonded fabric, etc. 
     Moreover, according to the invention, there are provided one or n inflatable elements  29 , inserted into special recesses  30  obtained on the central side surface  24  of the shaft according to longitudinal generating lines. The inflatable elements  29 , such as air tubes or the like, are fed from the outside with pressurised air through a pipe  31  connected to a rotating joint, schematised in  32 , fastened to the other end of shaft  20 . The pressure into the inflatable elements  29  can be regulated in function of the particular requirements from the outside, in a quick and simple manner, even during the operation of the braking roller into the system. 
     Moreover, according to the invention, one or n wear elements  34  are provided, one for each inflatable element  29 , arranged into recesses  30  and such as to fill them with the inflatable element  29 , so as to try to protrude inwards of each idle pulley  25 . In fact, the wear element  34  is made by the inflatable element  29  to abut against the inside surface of each idle pulley  25 . These wear elements  34  can be made of various types of material, for example felt, brake lining, etc., and they can be easily replaced by side extraction through suitable slits  35  obtained on the side containment flanges  27 . In case of bad operation, it is even possible to replace the inflatable elements  29 . 
     The operating principle of the braking roller  16 ,  17 ,  18  of the present invention is as follows: the roller is put into rotation by motor  21  connected to shaft  20  so that the peripheral speed corresponding to the outside surface of pulleys  25 , or of covering  28 , is slightly less than the speed of strip  14  of band  12 , which is slower. 
     In this way, each pulley  25 , pulled by strip  14  into contact with it, rotates—with respect to shaft  20 —at a slightly higher speed than the difference between its speed and the speed of the slower strip. 
     By suitable adjusting the feeding air pressure of the inflatable elements  29 , through the wear elements  34 , a resisting force is generated that opposes the rotation of the single pulleys  25  with respect to shaft  20 , thus creating the braking effect of strips  14  being wound on the final rolls  15 . 
     Since pulleys  25  are totally disengaged from one another, the difference of speed of strips  14  is totally compensated, with a winding tension that is perfectly even and distributed on the entire width. 
     The problems of known braking systems are thus solved in a simple, practical and inexpensive manner. 
     The presence of the pulleys, of the covering of the same, if present, and of the inflatable element and of the wear element allows the adjustment to the different speeds of the strips of the single portion of the braking roller in a functional, correct and practical manner. In fact, it is possible to guarantee a correct and even winding tension of the single strips, thus compensating the difference of speed that generates after possible differences of thickness between the strips. The presence of the pulleys, of the inflatable element and of the wear element, as well as of the pulley covering, allows a suitable adjustment. 
     In fact, it is possible to have a good adjustment also in case of strong differences between the various strips. 
     Moreover, there are no possibilities of scoring or defects on the strip surface since there is no difference of speed, and thus of entrainment, between the roller pulleys and the strips. Thanks to the rotation of the roller, which is motorised in  21 , the speed difference between pulleys  25  and shaft  20  is minimum, to the advantage of the wear element  34 . 
     Several modifications and variants can be made to the braking roller for systems for cutting metal bands into strips thus conceived, all falling within the invention; moreover, all details can be replaced with other technically equivalent details. In practice, the materials used as well as the sizes, can be of any type.