Ultrasonic Sealing Device

Abstract

An ultrasonic sealing device (100) is disclosed, the ultrasonic sealing device (100) comprising a sonotrode (101) for sealing packaging material, the sonotrode (101) comprising a piezoelectric transducer (102) that generates ultrasonic acoustic vibrations for the sealing, a housing (103), a power circuit (104) connected to the piezoelectric transducer (102) and enclosed in the housing (103), and an absorbent (105) disposed within the housing (103) that absorbs moisture from the atmosphere within the housing (103) to reduce humidity. A method (200) for controlling humidity within the ultrasonic sealing device (100) is also disclosed.

Description

[Technical Field]

[0001] The present invention relates to equipment for sealing packaging containers, and more particularly to an ultrasonic sealing device for sealing the packaging material of such packaging containers, and to a method for controlling humidity in such an ultrasonic sealing device. [Background technology]

[0002] In the manufacture of packaging containers, a web of packaging material is typically sealed longitudinally to form a tube around the fill pipe of a filling machine. A transverse seal is made on the tube, which is then filled with the desired liquid food product. A second transverse seal is made, which also excises the package from the entire tube of material. The filled package is then folded and formed to obtain the final package. Various sealing methods are used for this process, including induction sealing and ultrasonic sealing. The packaging material is typically composed of a paperboard base material coated on both sides with a thermoplastic resin material, such as polyethylene. The paperboard base material may also have a gas barrier layer, which may also be coated with a thermoplastic resin material. In ultrasonic sealing, ultrasonic energy transmits vibrations from an ultrasonic horn to the packaging material, generating heat in the thermoplastic resin material. The thermoplastic resin melts, compressing the opposing surfaces of the packaging material toward each other and sealing them together. Ultrasonic sealing systems utilize a piezo stack converter to convert electrical energy into mechanical energy. The piezo stack requires a high voltage, on the order of several thousand volts, to be supplied. Previous ultrasonic sealing systems typically rely on complex solutions to ensure that the sealing device operates within the required environmental conditions when such high voltages are applied. These previous solutions require more resources and maintenance. Furthermore, implementation is difficult due to compatibility issues with some packaging machine systems in the production line. For example, conveyor systems based on linear motor technology have been proposed to manipulate packaging containers in production lines. These conveyor systems typically include a closed-loop track and multiple movable objects or carts that move independently along the track by individually controlling multiple solenoids along the track. Therefore, implementation of ultrasonic sealing systems must accommodate such independently movable carts. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention aims to at least partially overcome one or more limitations of the prior art. In particular, it is an object to provide an improved ultrasonic sealing apparatus that allows for easier control of environmental conditions, particularly for high voltage piezoelectric power circuits, particularly when implemented in a conveyor system with multiple independently movable carts along a track. It is also an object to provide an associated method for controlling humidity in an ultrasonic sealing apparatus. [Means for solving the problem]

[0004] In a first aspect of the present invention, this is achieved by an ultrasonic sealing device comprising a sonotrode for sealing packaging material, the sonotrode comprising a piezoelectric transducer that generates ultrasonic acoustic vibrations for sealing, a housing, a power circuit connected to the piezoelectric transducer and enclosed in the housing, and an absorbent disposed within the housing that absorbs moisture in the atmosphere within the housing to reduce humidity.

[0005] In a second aspect of the present invention, this is achieved by a method of controlling humidity within an ultrasonic sealing device having a piezoelectric transducer that generates ultrasonic acoustic vibrations for sealing packaging material and a power circuit enclosed in a housing and connected to the piezoelectric transducer, the method comprising absorbing atmospheric moisture within the housing using an absorbent material disposed within the housing.

[0006] In a third aspect of the invention, this is achieved by the use of an absorbent material within the housing of the ultrasonic sealing device, the housing enclosing a power circuit connected to a piezoelectric transducer that generates the ultrasonic acoustic vibrations to seal the packaging material with said ultrasonic sealing device.

[0007] In a fourth aspect of the present invention, this is achieved by a packaging machine comprising an apparatus according to the first aspect and / or carrying out a method according to the second aspect.

[0008] Further embodiments of the invention are defined in the dependent claims, wherein features of a first aspect can be implemented in a subsequent aspect and vice versa.

[0009] By placing an absorbent material within the housing enclosing the piezoelectric power circuitry, atmospheric moisture within the housing can be absorbed, thereby preventing short circuits in the high voltage circuitry and component failure.

[0010] Further objects, features, aspects and advantages of the present invention will become apparent from the following detailed description and drawings.

[0011] Embodiments of the present invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which: [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of an ultrasonic sealing device. [Figure 2] FIG. 2 is a schematic diagram of a housing for the power circuit of the ultrasonic sealing device. [Figure 3] FIG. 1 is a schematic diagram of a conveyor system with multiple movable ultrasonic sealing devices. [Figure 4a] 1 is a flow chart of a method for controlling humidity in an ultrasonic sealing device. [Figure 4b] 1 is a flow chart of a method for controlling humidity in an ultrasonic sealing device. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. The invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0014] FIG. 1 is a schematic diagram of an ultrasonic sealing device 100 including a sonotrode 101 for sealing packaging material (not shown). The ultrasonic sealing device 100 includes a piezoelectric transducer 102 that generates ultrasonic acoustic vibrations to seal the packaging material for producing a package. The ultrasonic sealing device 100 includes a housing 103 and a power circuit 104 connected to the piezoelectric transducer 102. The power circuit 104 is a high-voltage circuit enclosed within the housing 103 for powering the piezoelectric transducer 102. The ultrasonic sealing device 100 includes an absorbent material 105 disposed within the housing 103 to absorb moisture from the atmosphere within the housing 103, thereby reducing humidity within the housing 103. By including the absorbent material 105 within the housing 103 of the power circuit 104, humidity can be controlled and kept below a critical level for the high-voltage piezoelectric power circuit 104, thus preventing condensation. If this precaution is not taken, condensation could cause a short circuit in the circuit 104 and component failure. Thus, complex systems previously used to control humidity, such as those using compressed air, can be eliminated. The complexity and cost of the ultrasonic sealing device 100 can be reduced while still adhering to the necessary environmental requirements of the power circuit 104. Furthermore, the reduced complexity facilitates implementation of the ultrasonic sealing device 100 in conveyor systems based on linear motor technology, in which the ultrasonic sealing device 100 is independently movable along a track, as further described in connection with FIG. 3 below. For example, installing a system using compressed air in such a conveyor system would increase its complexity and cost, potentially impacting the performance of the conveyor system and resulting in reduced operating speeds. Therefore, placing the absorbent material 105 within the housing 103 enclosing the piezoelectric power circuit 104 maintains the high performance of such conveyor systems utilizing independently movable sealing devices 100, enabling high production line throughput.

[0015] The ultrasonic sealing device 100 may include a container 106 for holding the absorbent 105 in a predetermined position within the housing 103. This allows for easy optimization of the position of the absorbent 105 and improved control of humidity within the housing 103. For example, some portions of the space within the housing 105 may be more prone to condensation. Furthermore, by holding the absorbent 105 in a predetermined position, a more robust ultrasonic sealing device 100 is provided, reducing the risk of the absorbent 105 interfering with adjacent components, as the ultrasonic sealing device 100 may be subject to rapid movement during different sealing operations. FIG. 2 is a schematic diagram illustrating an example of a container 106 for holding the absorbent 105 in a predetermined position within the housing 103. It should be understood that FIG. 2 is an example, and the container 106 may hold the absorbent 105 in various optimal positions depending on the configuration of the sealing device 100.

[0016] In one example, the container 106 may hold the absorbent material 105 in place adjacent the power circuit 104, as shown schematically in Figure 2. This further reduces the risk of liquid condensing near the high voltage components of the power circuit 104. Thus, safer operation of the ultrasonic sealing apparatus 100 is provided with less risk of component damage and interruption to the seal application and overall production line.

[0017] The container 106 may include a fastening element 107 for removably attaching the container 106 to the housing 103. Having the container 106 removably attachable to the housing 103 allows for easy installation and replacement of the absorbent material 105 as required, thus facilitating maintenance and minimizing the time spent on such replacement, thereby minimizing the impact on the production line.

[0018] The container 106 may be cylindrical, and the securing element 107 may include threads that can be threaded into the opening 108 in the housing 103. This provides for easy securing of the container 106 to the housing 103, and further facilitates subsequent removal of the container 106 for replacement of the absorbent 105. It should be understood that the container 106 and / or the housing 103 may include a variety of other securing elements 107, such as, for example, a clasp, a hook clip, a lock, a flange, a wire, etc., for removably attaching the container 106 to the housing 103. While a cylindrical container 106 with threads that can be threaded into the opening 108 in the housing 103 may provide a particularly easy and sturdy attachment, it is contemplated that the container 106 may have a variety of shapes, such as rectangular, oval, or circular, in combination with any of the above securing elements 107.

[0019] The container 106 may include a wall 109 surrounding the absorbent 105. The wall 109 may include a plurality of perforations 110, as shown schematically in FIG. 2 . Thus, the container 106 allows the absorbent 105 to be securely positioned within the housing 103, while the perforations 110 improve circulation of air within the housing 103 around the absorbent 105, thereby increasing the absorbent 105's uptake of moisture in the air and more effectively reducing humidity within the housing 103. The shape and number of the perforations 110 in the wall 109 of the container 106 can be varied to optimize contact between the absorbent 105 and the atmosphere within the housing 103.

[0020] The absorbent 105 may include a desiccant. A desiccant is a hygroscopic substance that induces or maintains a dry (dry) condition in its vicinity. That is, a desiccant is the opposite of a humectant. A desiccant may be a solid material that absorbs water. A desiccant may be in a form other than a solid and may function via other principles of water absorption, such as chemical bonding of water molecules. Having an absorbent 105 that includes a desiccant provides effective and resource-efficient control of atmospheric humidity within the housing 103.

[0021] The desiccant may include silica. Having a desiccant that includes silica not only allows for easier handling of the absorbent 105, but also allows for greater efficiency in terms of the resources required. The efficiency of a desiccant can be measured as the ratio of water that can be stored in the desiccant to its mass. In other examples, the desiccant may include activated carbon, and / or calcium sulfate, and / or calcium chloride, and / or molecular sieves such as zeolites, and / or hygroscopic polymers.

[0022] The ultrasonic sealing device 100 may include a sensor 111 for detecting moisture in the atmosphere within the housing 103. The sensor 111 may communicate with the controller 301, as shown schematically in FIG. 2 . The sensor 111 may communicate with the controller 301 via a wireless communication protocol. The controller 301 is configured to receive sensor data from the sensor 111. The sensor data may indicate the amount of moisture, i.e., the amount of water, in the atmosphere within the housing 103. Thus, the sensor 111 may detect the level of humidity in the atmosphere. The controller 301 may be configured to notify a user of a threshold level of moisture in the atmosphere. Thus, the measured moisture amount may be determined, for example, as an absolute humidity or relative humidity level and compared to a predetermined threshold level. If the predetermined threshold level is exceeded, the user may receive an alert notification. This provides easy humidity control for the ultrasonic sealing device 100, as such a notification may trigger replacement of the absorbent 105.

[0023] The ultrasonic sealing device 100 may include a frame 112, as shown schematically in the example of FIG. 1. The sonotrode 101 and housing 103 may be mounted to the frame 112, as further shown in FIG. 1. The ultrasonic sealing device 100 may include a track guide 113 configured to engage with a track 302 of a conveyor system 300, as shown schematically in FIG. 3, such that the frame 112 and ultrasonic sealing device 100 are movable along the track 302. The track guide 113 may include rollers disposed on either side of the frame to engage with the track 302. The conveyor system 300 may include a control unit 303 configured to control the individual positions of the multiple ultrasonic sealing devices 100, 100′ along the track 302. Having the ultrasonic sealing device 100 with the absorbent 105 as described above provides easy implementation in such a conveyor system 300 while effectively controlling the humidity level within the ultrasonic sealing device 100.

[0024] The housing 103 may be formed as an integrated enclosure within the frame 112. This provides a robust ultrasonic sealing device 100, while the absorbent material 105 allows for effective control of humidity levels in the space within the integrated enclosure.

[0025] FIG. 4a is a flowchart of a method 200 for controlling humidity within an ultrasonic sealing device 100. As described above, the ultrasonic sealing device 100 includes a piezoelectric transducer 102 that generates ultrasonic acoustic vibrations for sealing packaging material and a power circuit 104 enclosed in a housing 103. The power circuit 104 is connected to the piezoelectric transducer 102. The method 200 includes absorbing 201 atmospheric moisture within the housing 103 using an absorbent material 105 disposed within the housing 103. Thus, the method 200 provides the advantages described above in connection with the ultrasonic sealing device 100 and FIGS. 1-3. The method 200 also provides a reduced risk of component failure of the high-voltage piezoelectric power circuit 104 while facilitating implementation of the ultrasonic sealing device 100 in a packaging machine utilizing a conveyor system 300, as described in connection with FIG. 3.

[0026] 4b is another flowchart of a method 200 for controlling humidity within the ultrasonic sealing device 100. The method 200 includes detecting 202 a threshold level of moisture in the atmosphere within the housing 103 and notifying 203 the threshold level to a user. Thus, the moisture content measurement is detected, for example, as an absolute humidity or relative humidity level. When a predetermined threshold level is reached, the user receives an alert notification. This provides easy humidity control for the ultrasonic sealing device 100, as such a notification may trigger replacement of the absorbent 105.

[0027] A computer program product is provided that includes instructions that, when executed by a computer, cause the computer to perform the detection 202 and notification 203 steps of the method 200 as described above.

[0028] The use of an absorbent material 105 in the housing 103 of the ultrasonic sealing device 100 is provided, which has advantageous benefits as described above in connection with Figures 1-4. As previously mentioned, the housing 103 encloses a power circuit 104 connected to the piezoelectric transducer 102 for generating ultrasonic acoustic vibrations for sealing packaging material with the ultrasonic sealing device 100.

[0029] A packaging machine (not shown) is provided that includes the ultrasonic sealing apparatus 100 as described above in connection with Figures 1-2. Alternatively or additionally, the packaging machine performs the method 200 as described above. Accordingly, the packaging machine provides the advantageous benefits as described above in connection with the ultrasonic sealing apparatus 100 and the method 200.

[0030] From the foregoing description, while various embodiments of the present invention have been described and illustrated, the present invention is not limited thereto and may be embodied in other ways within the scope of the subject matter defined in the following claims.

Claims

1. A sonotrode (101) for sealing packaging material, comprising: a piezoelectric transducer (102) for generating ultrasonic acoustic vibrations for the seal; a sonotrode (101) comprising: a housing (103); a power circuit (104) connected to the piezoelectric transducer (102) and enclosed in the housing (103); an absorbent (105) disposed in the housing (103) that absorbs moisture in the atmosphere within the housing (103) to reduce humidity; Equipped with a frame (112) on which the sonotrode (101) and the housing (103) are mounted; a track guide (113) configured to engage with the track (302) such that the frame (112) is movable along the track (302).

2. 2. The ultrasonic sealing device of claim 1, further comprising a reservoir (106) for holding the absorbent material (105) in place within the housing (103).

3. The ultrasonic sealing device of claim 2, wherein the predetermined location is adjacent to the power circuit (104).

4. 4. The ultrasonic sealing device of claim 2 or 3, wherein the container (106) comprises a fastening element (107) for removably attaching the container (106) to the housing (103).

5. 5. The ultrasonic sealing device of claim 4, wherein the container (106) is cylindrical and the fixing element (107) comprises a thread that can be screwed into an opening (108) in the housing (103).

6. 6. The ultrasonic sealing device according to claim 2, wherein the container (106) comprises a wall (109) enclosing the absorbent (105), the wall (109) comprising a plurality of perforations (110).

7. The ultrasonic sealing device of any one of claims 1 to 6, wherein the absorbent (105) comprises a desiccant.

8. 8. The ultrasonic sealing device according to claim 7, wherein the desiccant comprises silica, and / or activated carbon, and / or calcium sulfate, and / or calcium chloride, and / or molecular sieves such as zeolites, and / or hygroscopic polymers.

9. 9. The ultrasonic sealing device according to claim 1, further comprising a sensor (111) for detecting moisture in the atmosphere, the sensor (111) being in communication with a control device (301) configured to notify a user of a threshold level of moisture in the atmosphere.

10. 10. The ultrasonic sealing device of claim 9, wherein the housing (103) is formed as an integral enclosure within the frame (112).

11. 1. A method (200) for controlling humidity in an ultrasonic sealing device (100) comprising: a piezoelectric transducer (102) for generating ultrasonic acoustic vibrations for sealing packaging material; a power circuit (104) enclosed in a housing (103) and connected to the piezoelectric transducer (102); a frame (112) to which a sonotrode (101) and the housing (103) are attached; and a track guide (113) configured to engage with a track (302) so that the frame (112) is movable along the track (302), comprising: absorbing (201) atmospheric moisture within the housing (103) using an absorbent (105) disposed within the housing (103); A method (200) comprising:

12. detecting a threshold level of moisture in the atmosphere (202); and notifying a user of said threshold level (203); The method of claim 11 , comprising:

13. A packaging machine comprising an ultrasonic sealing device (100) according to any one of claims 1 to 10 or carrying out the method (200) according to claim 11 or 12.

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