The present invention relates to an embossing system.
More particularly, the present invention relates to an embossing system in which glue is used to join together two or more webs of paper material to produce rolls of paper commonly called “logs” from which are obtained rolls of toilet paper, rolls of kitchen paper etc.
It is known that the production of logs of paper material, from which are obtained, for example, rolls of toilet paper or rolls of kitchen paper, implies the feeding of a web of paper, formed by one or more superimposed layers, on a predetermined path along which various operations are performed before proceeding to the formation of the logs, including a transversal pre-incision of the web to form pre-cut lines which divide it into separable tear-off sheets. The formation of logs implies the use of cardboard tubes, commonly called “cores” on the surface of which a predetermined amount of glue is distributed to allow the paper web to be bonded onto the cores gradually introduced into the machine which produces the logs, machine commonly called “rewinder”. The formation of the logs also implies the use of winding rollers located at the cradle, which impose on each core to rotate about its longitudinal axis thus determining the winding of the web on the same core. One of the rollers is located below the cradle, while other rollers are placed above the cradle. The process ends when a predetermined number of sheets is wound on the core, with the gluing of a flap of the last sheet on the underlying sheet of the roll thus formed (so-called “closing flap” operation). Upon reaching the predetermined number of sheets wound on the core, the last sheet of the log being completed is separated from the first sheet of the next log, for example by a jet of compressed air directed towards a corresponding pre-cutting line. At this point, the log is downloaded from the rewinder. The patent EP1700805 describes a rewinding machine that operates according to the above operating scheme.
The paper web used by the rewinding machine can be made up of several plies which are previously embossed and joined together by gluing in a unit comprising a predetermined number of embossing rollers to which is associated a gluing unit for distributing glue on at least one of the plies subjected to embossing. In general, the gluing unit comprises an anilox roller which picks up the glue from a special intake tank and a cliché roller which receives by contact the glue from the anilox roller and distributes it onto the veil to be glued. If the glue in the tank is insufficient or does not distribute correctly on the anilox roller, the contact between the latter and the cliché roller (the rollers in question rotate different speeds) causes overheating which, in particular, can damage the cliché roller.
The systems based on the temperature control of the cliché roller are inadequate because they are delayed since the detection of overheating occurs when this phenomenon has already occurred.
The main object of the present invention is to propose an embossing/gluing system provided with a particularly rapid and efficient control mechanism.
This result has been achieved, in accordance with the present invention, by adopting the idea of implementing a system having the characteristics indicated in claim 1. Other features of the present invention are the subject of the dependent claims.
In accordance with the present invention, provision is made to compare the vibrations of the cliché roller during operation with a reference model previously formed in a testing phase of the unit in which the cliché roller is installed, having observed that the vibrations of said component may vary according to the amount of glue actually present on its surface. The reference model can be constructed by running the embosser in different regimes, i.e. under conditions of correct and respectively incorrect distribution of the glue on the cliché roller, detecting its vibrations. During operation of the system, a sensor device detects the vibrations of the cliché roller and produces corresponding electrical signals which, converted into numerical data, are used by a control unit which compares them with the data detected and recorded in the reference model. If the instantaneous values detected during the use of the system differ from the previously acquired reference values, the control unit generates an electrical alarm signal that can be used to drive an acoustic and/or luminous signal and/or to control the stop of the plant or the slowing down of the units that form the plant itself until the correct operating conditions are restored. In the construction phase of the reference model, a sensor device is used, preferably the same device subsequently used when the system is in operation, suitable for producing electrical signals of amplitude and frequency related to the vibrations of the system under test.
By detecting the vibrations of the cliché roller during operation and comparing them with the data of a previously acquired reference model, it is possible to check in real time whether the cliché roller is adequately lubricated by the glue or not and therefore intervene in extremely short times to restore the conditions of correct operation, so as to significantly reduce the risk that this expensive component of the plant is damaged by an insufficient or in any case incorrect distribution of the glue on its surface.
These and further advantages and characteristics of the present invention will be more and better understood by any person skilled in the art, thanks to the following description and to the attached drawings, provided as an example but not to be considered in a limiting sense, in which:
The operating unit (OU) schematically represented in
According to the present invention, the aforesaid operating unit (OU) is controlled by a programmable control unit (1) which controls the motors (M1, M2) which determine the rotation of the embossing rollers and of the relative counter-rollers (G1, G2), the motors (MA, MC) of the anilox (AR) and cliché (CR) rollers, and the actuator (AS) which determines the movement of the mobile support (S) of the gluing unit (T, AR, CR). A sensor (2) able to detect the vibrations of the cliché roller (CR) is connected to a corresponding input of the control unit (1). For example, said sensor (2) is an accelerometer of the SKF CMSS2200 type. For example, this sensor (2) detects the vibrations of a bearing supporting one end of the cliché roller (CR) shaft in such a way as to detect the vibrations of the shaft itself. The sensor (2) produces electrical signals representative of the vibrations to which the cliché roller (CR) is subjected during its operation. In other words, the electrical signals produced by the sensor (2) are signals of amplitude and frequency determined by the vibrations of the cliché roller (CR).
In a step of carrying out the control system object of the present invention, the operating unit (OU) is operated under normal conditions (i.e. under conditions of proper lubrication of the cliché roller CR which receives glue from the anilox roller AR in sufficient quantity to guarantee lubrication), and in conditions of poor lubrication (i.e. in conditions of insufficient lubrication of the cliché roller CR which receives glue from the anilox roller AR in insufficient quantity to guarantee a correct lubrication), detecting the vibrations of the cliché roller (CR) in each of these operating conditions specially reproduced. Preferably, said vibrations are detected with the same sensor (2) subsequently used during operation of the system. Said measurements, i.e. the amplitude and/or frequency of the signals produced by the sensor used to detect the vibrations of the cliché roller (CR), are recorded in a data file (DB) which is used by the control unit (1) as further indicated below. For example, the file (DB) can be registered in a memory section of the control unit (1). In practice, during the formation of the file (DB), both normal and abnormal operating conditions of the unit (OU) are reproduced and data of amplitude and/or frequency of electrical signals produced by the vibrations of the cliché roller (CR) are recorded by a transducer that converts such vibrations into electrical signals. The data thus recorded are then used as a reference model in the phase of actual productive use of the operational unit (OU). In fact, during operation of the unit (OU), the control unit (1) continuously receives the data corresponding to the signals produced by the sensor (2) and compares them with the data of the file (DB). If the data related to the vibrations detected by the sensor (2) correspond to the data of the file (DB) representing anomalous operating conditions, the control unit (1) intervenes on the motors (M1, M2, MA, MC) to slow down the rotation of the rollers connected to them or also to stop the rotation thereof. In the latter case, the control unit (1) can also be programmed to drive the actuator (AS) so as to distance the gluing unit (T, AR, CR) from the embossing rollers.
Alternatively, with reference to
From the foregoing description it is evident that an embossing system according to the present invention comprises:
In practice, the details of execution may in any case vary in an equivalent manner as regards the individual elements described and illustrated, without departing from the scope of the solution idea adopted and therefore remaining within the limits of the protection conferred by the following claims.
Number | Date | Country | Kind |
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102017000011824 | Feb 2017 | IT | national |
Filing Document | Filing Date | Country | Kind |
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PCT/IT2018/000008 | 1/23/2018 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2018/142434 | 8/9/2018 | WO | A |
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International Search Report dated May 3, 2018 and Written Opinion of corresponding application No. PCT/IT2018/000008; 9 pgs. |
Number | Date | Country | |
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20190322068 A1 | Oct 2019 | US |