Patent Publication Number: US-2020277095-A1

Title: Method for operating a packaging machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application claims priority to German Patent Application No. 102019202755.5 filed on Feb. 28, 2019 to Peter Buchberger and Thomas Pfalzer, currently pending, the entire disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to the field of packaging machines for packaging products. 
     BACKGROUND OF THE INVENTION 
     Known packaging machines, such as thermoforming packaging machines or tray sealers, comprise work stations for carrying out processing steps for the production of a product packaging. For example, a sealing station can be provided which seals filled packaging trays or filled packaging trays thermoformed into a lower film web by sealing on a top film. The sealing station can comprise a heatable sealing tool for sealing the top film on by exertion of heat and pressure. Another example of a work station of a packaging machine is a forming station that forms packaging trays to be filled into a base film web by thermoforming. 
     Heating elements, for example in the form of a resistance heater, can be integrated into a tool of a work station for heating the tool. In order to keep the temperature of the tool in a suitable range during operation, a temperature sensor can also be provided in the tool, based on the sensor output of which the heating elements are operated according to a control procedure. It is known from practice that the heating elements are controlled by a central machine control device of the packaging machine. Corresponding switching elements for suitably supplying the heating elements with electric current, such as relays, can be provided in a control cabinet of the packaging machine. 
     It is known from DE 10 2016 125 132 A1 to provide a bus node arrangement at the individual work stations, such as a sealing station or a forming station, of a packaging machine, in which electronics is disposed that would have been disposed in the central control cabinet in conventional machines. The space requirement in the central control cabinet is thus reduced. The bus node arrangement is arranged on the outer side of the wall of the work station for easy access for maintenance purposes. Provided on a board of the bus node arrangement are, inter alia, electrical or electronic control elements for actuating a heating element of a tool of the work station. When the tool is installed in the work station, a connection of the tool, via which, for example, the heating elements are supplied with electrical current, is linked to a connection of the bus node arrangement. 
     DE 10 2016 117 834 A1 describes a sealing member that can be heated using heating conductors for the production of packagings made of thermoplastic materials such as plastic films. The sealing member comprises a housing that is formed to be attached to a packaging machine. Control electronics and/or a power electronics is to be arranged within the housing, so that the sealing member can be used autonomously, so the packaging machine itself does not have to effect the control or regulation function of the sealing member, because this is accomplished by the sealing member itself. The packaging machine only needs to provide the general energy supply and possibly the definition of certain target variables required for the sealing process, such as the target temperature. 
     The drawback in the operation of known packaging machines is that, at the start of production, a heating-up time of the heatable tools in the work stations must first be observed. Such a delay is particularly disadvantageous when resuming production after a tool changeover. Heating up the newly installed tool in the respective work station can indeed take some time and thereby delay resumption of production. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a method for operating a packaging machine which allows rapid resumption of production by simple means after a tool changeover. 
     The invention specifies a method for operating a packaging machine comprising a work station with an exchangeable tool. The method comprising the steps of providing a control device that may be integrated into the tool. Wherein, when the tool is in a state installed into the work station, the control device may regulate a temperature of the tool based on an operating temperature target specification by suitably supplying a heating device integrated into the tool with electrical power. Further, wherein, when the tool is in a state removed from the work station, the tool may be connected to an external power supply, and the control device may regulate the temperature of the tool based on a preheating temperature target specification by suitably supplying the heating device with electrical power provided by the external power supply. 
     The invention allows first preheating the tool in the state removed from the work station by connecting it to the external power supply by way of the control device based on the preheating temperature target specification. If the preheated tool is then installed into the work station, then packaging operation can optimally commence directly or at least faster than with a non-preheated tool since the tool temperature required during operation may already be available or at least reached faster. This may avoid or reduce any delay in the commencement of operation when the packaging machine is restarted or when the tool is exchanged. The installation of the preheated tool may require handling the hot tool. However, safe handling of the hot tool may be possible if appropriate protective measures are taken and the tool is adequately designed and staff is sufficiently trained. 
     It is particularly advantageous to have the temperature of the tool in the work station be regulated based on the operating temperature target specification (during packaging operation of the packaging machine) as well as the temperature of the tool in the removed state of the tool be regulated based on the preheating temperature target specification by the control device integrated into the tool. It may therefore not be necessary to provide a pre-heater with its own control device for preheating the tool outside the work station. It may instead be sufficient if the tool in the state removed from the work station may simply be connected to an external power supply which may provide electrical power for the operation of the heating device and electrical power for the operation of the control device of the tool. 
     Since the control device may be integrated into the tool itself, it may also be possible to operate tools that require differently configured control devices in the same work station and to connect them to the same external power supply. The configuration of the control device integrated into the tool can be respectively adapted to the properties of the tool, for example to the number, sizing and positioning of the heating devices in the tool. 
     The operating temperature target specification and/or the preheating temperature target specification can be temperature target values. However, it would also be conceivable to regulate the temperature of the tool not to a certain value, but to a certain range. The operating temperature target specification and/or the preheating temperature target specification could therefore also be formed as a target temperature range. 
     In one embodiment, the external power supply may provide the tool with electrical heating power, but not provide control or regulating signals. Controlling preheating can be taken care of entirely by the control device integrated into the tool. In addition to the electrical heating power, the external power supply can provide the tool with electrical power to operate the control device. For example, the external power supply can comprise a power cable, with or without a mains supply unit, for connecting to the tool and to a power outlet. However, it would also be conceivable to have the external power supply comprise a docking station into which the tool can be inserted or to which the tool can be docked. 
     According to one embodiment, the preheating temperature target specification of the control device may be determined by a machine control device of the packaging machine. The machine control device of the packaging machine can in particular transmit the preheating temperature target specification to the tool prior to the removal of the tool from the work station. If the tool is preheated prior to being reinstalled in the work station, this can be done based on the preheating temperature target specification previously transmitted by the machine control device of the packaging machine. In this way, the preheating temperature target specification can be adapted in a simple manner to the configuration of the packaging machine. In addition, it is possible without a great additional effort in time that the preheating temperature target specification may be specified to the tool based on user input at the packaging machine via the machine control device of the packaging machine. 
     It would also be conceivable that the preheating temperature target specification may be available to the control device as a preset specification, in particular “ex factory.” The preheating temperature target specification could be permanently stored in the tool itself. Combinations could also be conceivable in such a way that a standard value for the preheating temperature target specification may be initially available as a preset specification, but that it can be changed by the machine control device of the packaging machine in the state of the tool installed in the work station. 
     The control device may comprise a memory in which the preheating temperature target specification may be stored (for example as a preset specification or after transmission by the machine control device of the packaging machine). 
     According to one embodiment, the control device may be put into a preheating mode, in particular by the machine control device of the packaging machine, prior to the removal of the tool from the work station. After connection to the external power supply, the control device removed from the tool may recognize that it is in the preheating mode and may begin with regulating the temperature of the tool based on the preheating temperature target specification. When the tool is reinstalled into the work station, it can exit the preheating mode and be put into a packaging operating mode by the machine control device of the packaging machine in which it can regulate the temperature of the tool based on the operating temperature target specification. The control device can already be present in the preheating mode prior to a first installation in the work station (i.e. quasi “ex factory”). 
     It is conceivable that the control device, after connecting to the external power supply, may detect that there is no communication connection to a machine control device of the packaging machine, and may then start regulating the temperature of the tool based on the preheating temperature target specification. The preheating mode could therefore be recognized by detecting a lack of a communication connection to the machine control. It may then not be necessary for the machine control device to actively set the tool to the preheating mode. If the tool is reinstalled into the work station and a communication connection to the machine control device is established, then the control device could switch back to regulating the temperature of the tool based on the preheating temperature target specification. 
     The operating temperature target specification can be specified to the control device by the machine control device of the packaging machine. However, since the tool itself may comprise the control device, no further requirements are absolutely necessary on the part of the packaging machine except for a power supply and optionally specifying the operating temperature target specification. Specifying the operating temperature target specification by the machine control device of the packaging machine may allow for an adjustment of the temperature of the tool based on the respective operating situation of the packaging machine, possibly also during operation. Alternatively, however, it would also be conceivable that the operating temperature target specification may be already pre-stored in the control device. 
     In the state of the tool installed in the work station, the control device can be in communication connection with the machine control device of the packaging machine. For example, the preheating temperature target specification and/or the operating temperature target specification can be transmitted to the control device via this communication connection. However, it is also conceivable that the control device or other devices integrated into the tool could send data to the packaging machine via the communication connection. For example, transferring a tool ID would be conceivable. The communication connection between the control device and the machine control device of the packaging machine may be effected by way of a communication bus system. A corresponding bus node may be integrated into the tool. 
     In principle, the work station can be any work station of the packaging machine that comprises a tool to be heated. The work station may be a sealing station of the packaging machine, and the tool may be a heatable sealing tool for sealing a filled packaging, in particular by sealing on a top film. The work station could also be, for example, a forming station of the packaging machine and the tool could be a heating plate for heating a lower film web. The tool could in particular be a heatable form punch. 
     The invention may be applied to a packaging machine that is a thermoforming packaging machine or a tray sealer. However, it would also be conceivable to apply the invention to other packaging machines, for example a bag forming, filling and sealing machine. 
     At least one temperature sensor may be integrated into the tool, and the control device may use a value provided by the temperature sensor for regulating the temperature of the tool. In this way, regulating the temperature of the tool can be carried out particularly precisely. In addition, all components required for regulating may be integrated into the tool. 
     The temperature sensor and the control device can be integrated into the heating device as a joint module. This may reduce the manufacturing effort for the tool. Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures. 
    
    
     
       DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the following, an advantageous embodiment of the present invention will be explained in more detail making reference to a drawing, in which the individual figures show: 
         FIG. 1  is a schematic side view of one embodiment of a tray sealer for carrying out the method in accordance with the teachings of the present disclosure; 
         FIG. 2  is a schematic side view of one embodiment of a thermoforming packaging machine for carrying out the method in accordance with the teachings of the present disclosure; 
         FIG. 3  is a schematic section view of one embodiment of a work station with a heatable tool installed in accordance with the teachings of the present disclosure, where the work station is a sealing station; 
         FIG. 4  is a schematic block diagram representation of one embodiment of a tool that shows the tool in a state installed into a work station in accordance with the teachings of the present disclosure; and 
         FIG. 5  is a schematic block diagram representation of the tool according to  FIG. 4  that shows the tool being in a state removed from the work station. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures. 
     The following detailed description of the invention references specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled. 
     The invention relates to a method for operating a packaging machine  1 . According to an exemplary embodiment shown in  FIG. 1 , packaging machine  1  can be a tray sealer. Arranged consecutively on a machine frame  3  of packaging machine  1  along a production direction P are a destacking device  5 , a loading track  7 , and a sealing station  9 . Destacking device  5  destacks packaging trays  13  to be filled with products  11  onto a conveying device not shown in  FIG. 1 . Packaging trays  13  are conveyed along production direction P over a loading track  7  to a sealing station  9 . Packaging trays  13  are filled in loading track  7  with products  11  to be packaged. Filled packaging trays  13  are then closed in sealing station  9  by sealing on a top film  15 . For this purpose, sealing station  9  comprises a sealing station upper part  9   a  and a sealing station lower part  9   b  which can be moved relative to each other along a vertical direction to seal top film  15  onto packaging trays  13  received between them. Packaging machine  1  comprises a central machine control device  17  with electronic components for controlling packaging machine  1 . The machine control device  17  can also comprise a display and input unit  19 , for example in the form of a touchscreen display, with which an operator can manage functions of the packaging machine  1  and via which information about the operating status of packaging machine  1  can be displayed to the user. 
     The invention is also applicable to packaging machines  1  of other types. Shown as an example of this in  FIG. 2  is a packaging machine  1  configured as a thermoforming packaging machine. In the thermoforming packaging machine, no prefabricated packaging trays  13  are entered into the production process. Instead, a forming station  21  is provided which forms packaging trays  27  by thermoforming into a lower film web  25  that is drawn off a storage roller  23 . For thermoforming packaging trays  27 , forming station  21  comprises a forming station upper part  21   a  and a forming station lower part  21   b  which are movable relative to each other with respect to a vertical direction in order to form packaging trays  27  into lower film web  25  running between them. Lower film web  25  is conveyed by way of a transport device, not shown, along a production direction P of packaging machine  1 . After leaving forming station  21 , packaging trays  27  that are present as a composite are filled in a loading track  7  with products  11  to be packaged. Subsequently, filled packaging trays  27  are supplied to a sealing station  9  in which packing trays  27  are sealed by sealing on a top film  15 , similarly to sealing filled packaging trays  13  in the tray sealer from  FIG. 1 . Sealing station  9  in turn comprises a sealing station upper part  9   a  and a sealing station lower part  9   b  which are movable relative to each other. After packaging trays  27  have been sealed in sealing station  9 , the film composite is conveyed onward to a cutting station  29  in which the individual packaging is separated from the composite. The thermoforming packaging machine also comprises a machine control device  17  for controlling individual components of packaging machine  1 . Like machine control device  17  of the tray sealer from  FIG. 1 , it can comprise a display and input device  19  for the interaction with an operator. 
     Sealing station  9  of the tray sealer or sealing station  9  or the forming station  21  of the thermoforming packaging machine, respectively, are examples of work stations that perform a specific function in the respective packaging process.  FIG. 3  in schematic sectional view shows such a work station  9  in a configuration as a sealing station. However, the invention could also be applied to a forming station  21  as the work station. Work station  9 ,  21 , as mentioned, comprises a work station upper part  9   a ,  21   a  and a work station lower part  9   b ,  21   b  which are movable relative to each other along a vertical direction for processing the packagings. Work station  9 ,  21  comprises a heatable tool  31  for processing the packagings. In the embodiment according to  FIG. 3 , tool  31  is provided in work station upper part  9   a . A mating tool  33  is provided in work station lower part  9   b  and interacts with tool  31  for processing the packagings. However, it would also be conceivable that heatable tool  31  is provided in work station lower part  9   b  and mating tool  33  is present in work station upper part  9   a . In the embodiment shown, heatable tool  31  is a sealing tool, in particular a sealing frame. The mating tool can be formed as a backing element, so that the heatable sealing tool and the mating tool interact along a packaging edge for forming a sealing seam for sealing top film  15  onto the filled packagings. 
     Tool  31  can be heated in order to be able to process the packaging appropriately. For this purpose, a heating device  35  is integrated into tool  31 . In the variant shown in  FIG. 3 , heating device  35  comprises several heating elements  37 . The heating elements  37  can be formed in particular as electrical resistance heating elements or induction heating elements. 
     In addition, a bus node module  39  is integrated into tool  31  and in the state of tool  31  installed in the work station is in communication via a communication bus  41  of packaging machine  1  with machine control device  17  of packaging machine  1 . In the installed state of tool  31 , bus node module  39  is additionally supplied with electrical power by packaging machine  1  via an electrical connection  43 . 
       FIG. 4  in a representation as a schematic block diagram shows the configuration of bus node module  39  integrated into tool  31  as well as its integration into the overall system of packaging machine  1 , or into tool  31 , respectively, in the installed state of tool  31 . Bus node module  39  comprises a control device  45  for regulating a temperature of tool  31  by suitably supplying heating device  35  with electrical power. In the state of tool  31  installed into work station  9 ,  21 , control device  45  is connected via a communication module  47  to communication bus  41  and is thereby in communication connection with machine control device  17  of packaging machine  1 . Control device  45  comprises a processing unit  49  and a memory  51 . Processing unit  49  is configured to control switching elements  53  which determine a supply of heating elements  37  of heating device  35  with electrical power. The electrical power for the operation of heating elements  37  as well as the electrical power for the operation of control device  45  is provided by electrical connection  43  of packaging machine  1 . In addition, at least one temperature sensor  55  for measuring a temperature of tool  31  is integrated into tool  31 . In the variant shown, temperature sensor  55  is also provided in bus node module  39 . However, it would also be conceivable to integrate temperature sensor  55  elsewhere in tool  31 . Measured values of temperature sensor  55  are provided to control device  45 . 
     When installing tool  31  in work station  9 ,  21 , or when starting up work station  9 ,  21  with tool  31  installed, control device  45  is put into a packaging operating mode by machine control device  17  of packaging machine  1 , if it is not already in the packaging operating mode. In the packaging operating mode, control device  45  regulates a temperature of tool  31  based on an operating temperature target specification by suitably supplying heating device  35  with electrical power (by appropriately controlling switching elements  53 ). This ensures that the temperature of tool  31  is maintained in a range suitable for processing the packagings. The operating temperature target specification can specify a temperature target value or a temperature target range. The operating temperature target specification of control device  45  is preferably transmitted via communication bus  41  by machine control device  17  of packaging machine  1 . The operating temperature target specification can be determined automatically by machine control device  17  based on stored values and/or operating parameters of packaging machine  1  or can be set by user input. The operating temperature target specification can be stored at least temporarily in memory  51  of control device  45 . 
     In order to avoid or reduce delays caused by the initial heating up of tool  31  when starting up the packaging machine or upon resumption of the packaging operation after tool  31  has been exchanged (for example due to a change of format), tool  31  is preheated according to the invention already outside work station  9 ,  21 . For this purpose, tool  31  in the state removed from work station  9 ,  21  is connected to an external power supply  57 . 
       FIG. 5  in a representation as a schematic block diagram shows tool  31  in the state removed from the work station and connected to external power supply  57 . External power supply  57  provides electrical heating power to supply heating device  35  in tool  31  and a supply voltage for control device  45 . However, in one embodiment, no regulating or control signals are provided by external power supply  57 . The external power supply can comprise, for example, a power cable, with or without a mains supply unit, that can be connected to tool  31  and to a power outlet. 
     Controlling the temperature of tool  31  during preheating is likewise effected by control device  45  integrated into tool  31 . Control device  45  is put into a preheating mode by machine control device  17  of packaging machine  1  prior to the removal of tool  31  from work station  9 ,  21  or is in the preheating mode once the connection to machine control device  17  via the communication bus  41  is lost. Control device  45  can also be in the preheating mode ex factory. If tool  31  is connected to external power supply  57  while control device  45  is in the preheating mode, or without an active communication connection to machine control device  17 , respectively, control device  45  recognizes that it is in preheating mode and regulates the temperature of tool  31  by suitably supplying heating device  35  with electrical power provided by external power supply  57  based on of a preheating temperature target specification. The preheating temperature target specification can be stored in memory  51  of control device  45 . The preheating temperature target specification can be present in memory  51  in particular as a preset specification. However, it is also conceivable that the preheating temperature target specification of control device  45  was previously transmitted in the state of tool  31  installed into work station  9 ,  21  by machine control device  17  of packaging machine  1  and stored in memory  51 . The preheating temperature target specification could be determined automatically by machine control device  17  of packaging machine  1  based on stored data and/or an operating condition of packaging machine  1  or be determined based on user input. 
     Tool  31  preferably comprises a signal device  59  which is controlled by control device  45  to output a signal that indicates a termination of the preheating process. For example, signal device  59  could be an LED that flashes during the preheating process and illuminates continuously once the preheating process has been completed. 
     After the preheating process has terminated, tool  31  is disconnected from external power supply  57  and installed into work station  9 ,  21 . Tool  31  is then connected to power supply  43  and communication bus  41  of packaging machine  1  by way of connecting suitable plug-in devices. Machine control device  17  of packaging machine  1  then puts control device  45  via communication bus  41  from the preheating mode back into the packaging operating mode in which the temperature of tool  31  is regulated based on the operating temperature target specification. 
     Due to the fact that tool  31  was preheated before the installation into work station  9 ,  21 , the operation of packaging machine  1  can ideally start immediately after tool  31  has been installed. 
     From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting. 
     The constructions and methods described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention. 
     As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required.” Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.