Abstract:
A cutting head for rolls ( 12 ) of kitchen towel or toilet paper, positioned on a cutting machine ( 11 ) on which at least two rolls ( 12 ) are conveyed step by step by a pusher conveyor, the cutting head ( 17 ) being connected to a motorized cutting disc ( 20 ), the cutting head ( 17 ) cutting the rolls ( 12 ) crosswise, the rolls ( 12 ) being set on a surface of a conveyor ( 14 ), where the rolls ( 12 ) are guided through grooves ( 13 ), wherein the cutting head ( 17 ) is connected to a rotary arm ( 26 ) affixed to sleeve ( 24 ) which is affixed to a supporting structure ( 21 ), the cutting head ( 17 ) further comprising a rotary shaft ( 47 ) for at least one cutting disc ( 20 ).

Description:
The present application claims priority to Italian Patent Application Serial No. MI 2000A 001227, filed Jun. 1, 2000. 
     BACKGROUND OF THE INVENTION 
     The present invention refers to a cutting head for several rolls of kitchen towel and/or toilet paper. 
     It is known that, for the production of rolls of kitchen towel and/or toilet paper, starting from batons or wound rolls of a predetermined diameter and of a certain height, e.g. approximately two meters, and known as logs, they must be cut so as to produce single rolls, e.g. approx. 200 mm in length, ready for distribution. 
     Presently, the cutting of these final rolls to the predetermined measurement is carried out on special cutting machines which receive, for example, the single log and cut it in sequence into a large number of shorter rolls, each of the required size. The log, upon completion of its take up reaches a pusher conveyor, which sets it out underneath a cutting machine. 
     In general, such a machine includes a motorized cutting disc on an arm which rotates, passing from a release position of one or two underlying logs, advanced on the conveyor, to a take up position to cut one or more rolls from the respective logs and so on. 
     Based on this working pattern, the disc engages with the logs or rolls to be cut, at most four underlying logs, according to strictly circular trajectories which limit the diameter of the logs to be cut because of possible problems of interference between the parts. Since the logs are set according to a chord as regards the revolution circumference of the disc, the middle logs are engaged with the cutting blade to a greater extent. As the cutting blade thickness increases towards the centre, an uneven cut is produced and the blade overheats. 
     To accelerate such parting operations, cutting machines are also produced which actually follow the log or logs during their advancement on the pusher conveyor and cut them while moving to save time. 
     However, such devices are particularly complex and must be perfectly adjusted so as to not cut different sized or imperfectly cut rolls which do not match user requirements. In addition, they present the same problems of the aforesaid rotary arm devices. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to produce a cutting head for several rolls of kitchen towel and/or toilet paper which solves the previously mentioned problems. 
     Another object of the present invention is to produce a log cutting head that is extremely simple and practical, while allowing a fast cutting operation with high productivity. 
     Another object of the present invention is to produce a log cutting head that allows discs to be used up until a fairly limited diameter, with cost savings and fewer interruptions proving necessary for disc replacement. 
     These and other objects, according to the present invention, are reached by producing a cutting head for several rolls of kitchen towel and/or toilet paper positioned on a cutting machine ( 11 ) on which at least two rolls ( 12 ) are conveyed step by step by a pusher conveyor, said cutting head ( 17 ) being connected to a motorized cutting disc ( 20 ), said cutting head ( 17 ) cutting said rolls ( 12 ) crosswise, said rolls ( 12 ) being set on a surface of a conveyor ( 14 ), where said rolls ( 12 ) are guided through grooves ( 13 ), wherein said cutting head ( 17 ) is connected to a rotary arm ( 26 ) affixed to sleeve ( 24 ) which is affixed to a supporting structure ( 21 ), said cutting head ( 17 ) further comprising a rotary shaft ( 47 ) for at least one cutting disc ( 20 ), said rotary shaft ( 47 ) of said cutting disc ( 20 ) being rotated by a motor ( 38 ) connected to said rotary shaft ( 47 ) by a set of gears ( 45 ,  46 ,  48 ) are supported and are eccentrically movable in relation to a drive shaft ( 32 ) while carrying out a cutting operation according to a synchronous ratio, said drive shaft ( 32 ) transmitting rotation to said cutting disc ( 20 ) and being parallel to a rotational central shaft ( 22 ) of said rotary arm ( 26 ). 
     Further characteristics are envisaged in the dependent claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The characteristics and advantages of a cutting head for several rolls of kitchen towel and/or toilet paper, according to the present invention, will become apparent from the description that follows, supplied simply as explanatory and non-limiting, referring to the schematic drawings, in which: 
     FIG. 1 is a schematic front view of a two head cutting for rolls of kitchen towel and/or toilet paper according to the present invention assembled on a cutting machine; 
     FIG. 2 is a plan view from above of a part of the machine in FIG. 1 with sections of the two heads according to the invention, 
     FIG. 3 is an enlarged sectional view of a detail of FIG. 2, 
     FIG. 4 is a perspective view of the head of the present invention, assembled on a machine; 
     FIG. 5 is a schematic view of the course covered by the blades with the head of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1 is shown a cutting machine for several rolls of kitchen towel and/or toilet paper indicated as a whole by  11 , being equipped with two heads according to the invention. 
     The cutting machine  11  is positioned below a pusher conveyor (not shown) which supplies logs  12 , for instance using pushers, to be cut to the predetermined measurement in a succession of rolls. In the example, the feed is according four grooves  13  positioned on a surface of the conveyor  14 . In the example, the feed provides step by step advancement of predeterminable quantities of logs to be cut. Then, pressing parts (not shown) are in general envisaged which hold the logs  12  and engage on these, when they have been advanced a certain amount under the cutting machine  11 . 
     The cutting machine  11  may include a lower supporting structure  15  and an upper portal structure  16 , which can be raised and/or lowered in relation to the lower structure  15 . 
     The portal structure  16 , which has two cutting heads  17  of the cutting machine has rectangular section hollow guides  18  able to slide on I-beam uprights  19  which extend upwards, fixed to the lower structure  15  and height adjustable according to requirements. In this manner, it is possible to adjust the position of the cutting discs  20  of the two heads  17  depending on the diameter of the logs  12  and the diameter of the cutting discs  20 . This portal structure  16  is appropriately moved and operated with centralized controls, not shown. In any case, it is possible to set the cutting heads of the invention also on a fixed structure, for example on a fixed crossbeam  21 . 
     Instead, in the example shown, the crossbeam  21  connects the hollow guides  18  and supports a ratiomotor  23  which rotationally controls a central shaft  22 . 
     On a sleeve  24  fixed to the crossbeam  21  and externally coaxial to central shaft  22 , which goes through to its interior, is supported a rotary arm  26 , with the interposition of bearings  25 , which bears the pair of cutting heads  17  of the cutting machine  11 . In the example, the rotary arm  26  extends from opposite sides in relation to said central shaft  22  and bears two heads, but a simplified machine could also have just one head. This rotary arm  26 , at its free, opposite ends bears, by bearings  27 , a shaped case  28  equipped with a sleeve extension  29  which bears a belt pulley  30  constrained at one of its free ends, which is integral with it. The belt pulley  30  and the shaped case  28  in turn support, by additional bearings  31 , a drive shaft  32  which transmits the rotation to the cutting disc  20 , parallel to the rotation central shaft  22  of the rotary arm  26 . The drive shaft  32  which transmits the rotation to the cutting disc  20  in turn bears an additional belt pulley  33  constrained at one of its free ends, which draws the motion through belt  34  from a pulley  35  placed externally coaxial to the sleeve  24  fixed to the crossbeam  21  and on the same rotation due to the presence of bearings  36 . 
     The pulley  35  is integral with a second pulley  35   a  joined and constrained to it, this also set on bearings  36 , and fit to receive the motion through a timing belt  37  controlled by a motor  38  integral with the crossbeam  21 . The pulleys  35  and  35   a  act as transmission, concentrically set at the rotation fulcrum of the rotary arm  26 . 
     Also to be noted is the presence of a pulley  39  fixed and placed externally coaxial to the sleeve  24 , fixed to crossbeam  21 , on which passes a timing belt  40  which thus causes the case  28  to rotate around the drive shaft  32 . Naturally, idle tension rollers are envisaged  41  and  42 , respectively for the belts  40  and  34  positioned on the rotary arm  26 . 
     It must not be forgotten that the rotary arm  26  is rotationally dragged by the central shaft  22  due to the presence of a transmission flange of the motion  43  placed at the end of the central shaft  22  and constrained at an external support  44  by bearings  25  which bear the same rotary arm. 
     Returning to each of the cutting heads  17  it should be noted that the drive shaft  32  which transmits the rotation to the cutting disc  20  bears a gear  45 , at its other free end, opposite that where the pulley  33  is positioned, which in turn meshes with a second gear  46 , eccentric in relation to drive shaft  22 . The gears  45  and  46  are oil-bath lubricated in the shaped case  28 . A lay shaft  47 , the proper drive shaft of the cutting disc, bears this second gear  46 , and is this which goes into an epicyclic reduction gear  48 , with differential function, at the exit of which is supported the cutting disc  20 . Both the pair of gears  45  and  46  as well as the reduction gear  48  are housed within the shaped case  28  which turns around drive shaft  32  which transmits the rotation to the cutting disc  20 . 
     The rotary arm  26  thus bears two eccentric cutting heads  17 , at its diametrically opposite ends, which turn at a synchronous ratio of 4:1 in relation to the rotation of the same arm around its own axes  47 . The shaped case  28  is supported by bearings  27  and motorized by the timing belt transmission  40  and belt pulleys  30 ,  39  with a 4:1 ratio in relation to the rotation of arm  26 . It should be noted that the motion of eccentric rotation of cases  28  or heads  17  is indeed conferred by the rotation of arm  26 . 
     In fact, the pulley  39  is locked on the sleeve  24 , or on the rotation fulcrum of the same arm  26 . 
     With such a structure of each of the heads  17  set on rotary arm  26  each cutting disc is operated to make a closed ring course with four flattened sides, as in that shown in FIG.  5 . 
     In the lower part of such course, a virtually straight section and parallel to the conveyor  14  surface, denoted by A to B in the section covered, the disc  20  acts on the underlying logs  12  set in grooves  13 , cutting rolls (not shown) of the previously defined and chosen measurement. 
     The example shows how said two heads  17 , set on the rotary arm  26 , each bearing a disc or blade  20 , intervene consecutively after the cutting action of one of the discs on the stationary logs, the logs advance and these advanced logs are cut by the other disc to the predetermined size. In this way the discs are cooled between one cut and another with improved cutting quality. 
     It is clear that disc sharpening systems, protection for the rotating and moving parts and adjustment units for the logs and rolls thus obtained are possible for completion of the machine. 
     It is superfluous to say that the cutting heads of the present invention, once joined to a cutting machine, allow the same to function without interruption. In fact, the rotation of the rotary arm, bearing any number of discs or blades, ensures continuous operation of the machine. 
     Advantageously, the discs exert their cutting action on the virtually straight A-B section of the closed flattened ring course with a restricted curved entry and exit space C, resulting in an improvement in the cutting quality. This is without doubt due to the geometry of the cutting trajectory and the slower advancement speeds of the disc in the material, due to the shorter run required for each cut. Furthermore, due to the straight trajectory the cutting disc or blade rim in use is less and constant. 
     In fact, the known rotary arm cutting machines cut according to an arc of a circle which, upon contact with the logs, generates a circular cut trajectory with gradual log contact, a variation in the blade or disc thickness and a partially correct cut. To be able to cut, for example, many logs or rolls it is necessary to have a particularly large rotation circumference of the arm which gives increased cutting speeds to the detriment of the quality of the product obtained. These problems increase with a reduction in diameter of the cutting disc through wear. The present invention can avoid all this due to the collaboration of movements at the prefixed synchronous ratios. 
     Moreover, it is possible based exactly on the contact according to an almost straight course of the cutting disc during its operating stage to work on logs of greater diameter without problems of interference with machine parts and intolerable variations in thickness of the disc areas coming into contact with the log to be cut, as happens with the rotary arm machines known until now. In this manner, one can work with discs of reduced diameter on logs of a certain diameter, which was not possible with the previous machines. 
     With this head applied on a cutting machine one also makes the cut according to several grooves for various logs simultaneously, with increased productivity. Such an operation is not possible with a rotary arm according to a circular trajectory which presents operating limits due to its geometry and cannot work on more than three-four logs simultaneously. 
     In any case, it is possible to use also more discs than those indicated simply by replacing the diametrical arm with a cross arm. 
     If the possibility exists of height adjustment of the upper portal structure  16 , movable up and/or down in relation to the lower structure  15 , then adjustment of the distance both depending on the diameter of the logs  15  as well as on the diameter of the cutting disc is possible. Actually, by lowering the upper portal structure  16  it is possible to fully exploit the cutting discs  20  with a gradual reduction in diameter due to the cuts made. 
     For example, movement can be carried out using jacks such as that shown in  49  in FIG. 2 which envisage the rapid positioning of the parts depending on the disc diameter and/or the diameter of the log to be cut. 
     A cutting head, according to the invention for a cutting machine, thus solves all the problems of the previous technique and allows, in a simple and reliable manner, the processing of several rolls of any diameter, in any number, without any problems, resulting in high cutting productivity.