Air cooled cutting roller in a labelling machine

Abstract: The invention falls within the field of labelling machine with the continuous introduction of a reeled label film. In particular, it relates to the cutting roller (1) of the label film and it comprises an air cooling line for the two support systems of the shaft (5) of the cutting roller. The cooling line is preferably independent for each of the two systems and it comprises a probe (10 or 11) for measuring the temperature of the related support which sends its measured value to a block (22) for its comparison with a pre-set preferential temperature value. The block (22), according to the compared value, activates a solenoid valve (23) inserted on the compressed air supply circuit.

Description: The present invention relates to a cutting roller in a labelling 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. Labelling 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 millimetre, 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 forcedly to carry oil, heated at a temperature exceeding that of the external environment by about 20-30 °C, into the roller support frame. This allows to heat said support frame to a temperature of a bout 50 °C before starting the labelling cycle, and to maintain said temperature during the work of the machine. The solution provided in the aforementioned patent, while it technically solves the problem for labelling machines with high production rates (60,000 labels per hour), has been found unsuitable for machines with lower production rates (30,000 labels per hour). Moreover, the system for maintaining temperature with oil has created leakage problems in correspondence with the seals of the hydraulic circuit. 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 labelling machine with the continuous introduction of a reeled film of labels, constituting the subject of the present invention, which is characterised by the content of the appended claims. 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 preferably 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. 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: Figure 1 shows a cutting roller in a vertical section; Figure 2 shows the cutting roller in the section I-I of Figure 1; Figure 3 shows a longitudinal section view of the upper support of the cutting roller shaft; Figure 4 shows the support of the cutting shaft according to section 3-3 of Figure 3. 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 2a and two cross members, an upper one 2b and a lower one 2c. In the upper cross member 2b is inserted a bushing 3 in which is inserted a bearing 4 that supports a motorised 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 2c. In the bushing 3 is provided, as better shown in Figure 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 2c 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 2c is provided an inlet 12 for compressed air which feeds a duct 13 that rises along one of the columns 2a 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 2a 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 2c 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 not shown herein, compressed air may also be cooled by means of a heat exchanger 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.

Claims: A cutting roller (1) in a labelling machine with continuous introduction of a reeled film of labels of the type comprising a frame (2) which sustains two support systems, an upper (3, 4) and a lower (6, 7) system, for a motorised roller shaft (5) whereon is keyed the cutting roller (1), characterised in that in said frame (2) is obtained at least a compressed air line (13-17, 20) for cooling said support systems (3, 4 and 6, 7). A cutting roller as claimed in claim 1, characterised in that it comprises at least a probe (10, 11) for measuring temperature in correspondence with at least one of the support systems (3, 4, 6, 7) of the roller shaft (5). A cutting roller (1) as claimed in claim 1, characterised in that the frame (2) comprises in combination a first compressed air line (13-17) which provides for cooling the upper support system (3, 4) of the cutting roller (1); a second compressed air line (20) which provides for cooling the lower support system (6, 7) of the cutting roller shaft (5), each support system (3, 4 and 6, 7) being provided with a temperature measuring probe (10 or 11) connected with a block (22) for comparing with a pre-set ideal temperature value, the comparison block (22) activates a solenoid valve (23) which opens or closes the respective compressed air line (13-17, 20) according to the value obtained by the comparison block (22). A cutting roller (1) as claimed in claim 1, characterised in that the compressed air line (13-17) which provides for cooling the upper support system (3, 4) of the cutting roller (1) comprises an annular chamber (15) obtained in a bushing (3) included in the upper support system (3, 4) of the roller shaft (5). A cutting roller (1) as claimed in claim 1, characterised in that the compressed air cooling system comprises a heat exchanger for cooling air before its entry into the compressed air lines (13-17, 20) obtained in the frame (2).

Inventors: SCHINELLI NICOLA, SCHINELLI, NICOLA
Applicants: SIG ALFA S P A, SIG ALFA S.P.A.
Application year: 2000
Main classification: B65C9
IPC codes: B26D7, B65C9