Patent Publication Number: US-6658975-B2

Title: Cutting roller in a labeling machine with the continuous introduction of a reeled film of labels

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a cutting roller in a labeling machine with the continuous introduction of a reeled film of labels. In particular, the cutting roller finds its most extensive use to cut into segments or labels a thin film of polypropylene or PVC or plastic film in general whereon are printed the images and data constituting the label. It could nonetheless also be used for films made of other materials, for instance paper. Labeling machines that employ label films generally comprise: 
     an assembly for unwinding the reeled film; 
     a cutting assembly constituted by a vertical blade mounted on a roller rotating about a vertical axis, which in the technical jargon is called cutting roller, and by a fixed vertical counter-blade; 
     a drum for picking up and transferring the cut label towards a roller for spreading the glue which intervenes in predetermined areas of the label and subsequently on the container whereon the label itself is to be applied. 
     Both the cutting roller, bearing the blade, and the pick-up drum are provided internal chambers in which a vacuum is created and which communicate through a plurality of holes with the outer surface of the cutting roller or of the drum to attract and hold the labels while they are cut and transferred onto the drum and to retain them on the drum itself. 
     The cutting of the film, which in some cases has a thickness of a few hundredths of a millimeter, presents several problems due mainly to the flexion or deformation of the support of the cutting roller. Said flexion or deformation occurs mainly because of the inconsistent and inconstant heat expansions in the whole cutting roller. In particular, it is evident that at the start of the work process the supports of the cutting roller have low temperatures which progressively increase as the hours of work increase, so that one is forced to adjust the position of the counter-blade during the working period. 
     To overcome the aforesaid drawback, the same Applicant has provided a cutting roller (protected by Italian industrial invention Patent No. 1294078) which comprises ducts able to carry oil, heated at a temperature exceeding that of the external environment by about 20-30° C., into the roller support frame. These ducts allow for heating said support frame to a temperature of about 50° C. before starting the labeling cycle and for maintaining said temperature during the work of the machine. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to eliminate the aforesaid drawbacks and to make available a cutting roller provided with a cooling system able to maintain constant the temperature of the supports of the cutting roller, exploiting compressed air at ambient temperature. A first advantage is thereby obtained of not having heating systems with the consequent lower operating costs. A second advantage consists of the lack of costly seal elements, with no leakage problems, since the cooling fluid is air. 
     Said aims are fully achieved by the cutting roller in a labeling machine with the continuous introduction of a reeled film of labels, constituting the subject of the present invention, which is characterized by the contents of the claims set out below. 
     In particular, the cutting roller comprises, in correspondence with the two supports of its rotation shaft, ducts wherein compressed air at ambient temperature is sent. In correspondence with said supports are provided temperature detection probes which activate or inhibit the flow of air by acting on appropriate solenoid valves inserted on the compressed air supply line. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This and other features shall become more readily apparent from the following description of a preferred embodiment illustrated, purely by way of non limiting example, in the accompanying drawing tables, in which: 
     FIG. 1 shows a cutting roller in a vertical section; 
     FIG. 2 shows the cutting roller in the section I—I of FIG. 1; 
     FIG. 3 shows a longitudinal section view of the upper support of the cutting roller shaft; 
     FIG. 4 shows the support of the cutting shaft according to section  3 — 3  of FIG.  3 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to the figures, the reference number  1  globally indicates a cutting roller of essentially cylindrical shape and whereon are mounted systems for locking a blade of a known type, not shown herein. The cutting roller  1  is supported by a portal shaped frame  2 , i.e. comprising two columns  2   a  and two cross members, an upper one  2   b  and a lower one  2   c . In the upper cross member  2   b  is inserted a bushing  3  in which is inserted a bearing  4  that supports a motorized shaft  5  whereon is keyed the cutting roller  1 . 
     Inferiorly to the shaft  5  is inserted a bearing  6  housed in a seat  7  obtained in the lower cross member  2   c . In the bushing  3  is provided, as better shown in FIG. 3, a hole  8  in which is inserted a probe  10 , of a known kind, for measuring the temperature of the bushing itself. In the lower cross member  2   c  is provided another hole  9  for the insertion of a probe  11 , of a known kind, for measuring the temperature in correspondence with the seat  7  of the bearing  6 . In the lower cross member  2   c  is provided an inlet  12  for compressed air which feeds a duct  13  that rises along one of the columns  2   a  and feeds a horizontal duct  14  which ends in an annular chamber  15  encompassing the whole bushing  3 . Another horizontal duct  16  coming from the annular chamber  15  is connected with a vertical duct  17  obtained in the other column  2   a  and discharging into the external environment through a known silencing device  18 . A first compressed air line is thereby created which thus provides for cooling the upper support system of the cutting roller shaft. Inferiorly directly in the lower cross member  2   c  is provided a second compressed air inlet  19  connected with a second line  20  which encompasses the seat  7  of the bearing  6 . The compressed air that is sent into the second line  20  exits through a silencing device  21 . The second circuit  20  supplied with compressed air therefore serves the function of cooling the seat of the bearing  6 . 
     Both bearings  4  and  6  are lubricated by greasing. 
     It has been observed that the ideal temperature whereto bushing  3  and seat  7  need to be maintained lies in a range between 35 and 50° C. Hence, a device is provided for controlling and maintaining the ideal temperature which is pre-set at the start of the working cycle also according to the type of material constituting the label film. The control device comprises the two probes  10  and  11  which measure the temperature respectively of the bushing  3  and of the seat  7  and transmit the measured value to a comparison block  22  whereon the ideal temperature value is pre-set. If the measured temperature exceeds the value of ideal temperature, the comparing block acts on a solenoid valve  23  which opens the compressed air line, thereby starting to blow cooling air. The cooling line for the bushing  3  is fully independent from the cooling line for the seat  7  so that cooling can act either simultaneously or independently on bushing  3  and/or seat  7 . 
     Lastly, the bushing  3  with related bearing  4  and the seat  7  with related bearing  6  constitute two support systems which are maintained at a pre-set constant temperature by at least a compressed air cooling line. 
     In the description, specific reference has been made to two independent compressed air cooling lines, but it is evident that the circuit could also be a single one, shared by the upper bushing  3  and by the seat  7 , and it is obvious that in this case the ability independently to control temperatures in two points will not be available. The compressed air used is air at ambient temperature but, according to a possible variation shown in FIG. 2, compressed air may also be cooled by means of a heat exchanger  30  before its entry into the cooling line. The cutting roller  1  described above therefore has the following advantages: 
     use of compressed air, whose intervention is not constant but commanded only under determined temperature circumstances, hence with limited operating costs; 
     practically non-existent or utterly minor sealing systems; 
     possibility to adjust temperatures on the upper support systems independently from the lower support system; 
     better control over the temperature of the bearings which could have different heating due to different greasing.