Patent Description:
The consumer packaged goods industry typically utilizes thin film materials coated with a thermally activated sealant layer, in combination with resistively heated thermal jaw systems, for sealing packages used to contain various food products. Thermal sealing technology is commonly used on packages that are between <NUM>,<NUM>-<NUM>,<NUM> (<NUM>-<NUM> inches) in width and to maintain acceptable seal integrity for perishable products, the thermal seal region is oversized to reduce gas leak rates. However, these large thermal seal areas are known to still experience high rates of gas leakage. Large thermal seal areas also result in higher material costs and the high gas leak rate results in shorter shelf life for the products contained in this type of package. Additionally, currently used thermal sealing systems and methods are not capable of effectively sealing through even a minimal amount of food or other product that has entered the seal region of a package. This problem leads to higher factory scrap and an increased likelihood of delivering spoiled or unusable product to the consumer.

Previous attempts have been made to introduce ultrasonic sealing technology to consumer packaged goods with little or no adoption thereof by the industry. Current ultrasonic sealing technology does not provide a solution that can be used in mass production to seal thin or thick films having widths of over <NUM>,<NUM> (<NUM> inches).

Ultrasonic sealing methods are available which allow for sealing limited package widths (e.g., up to <NUM>,<NUM> (<NUM> inches)) using a single transducer, while sealing greater widths may be accomplished only by using multiple transducer systems. Most users of sealing systems require the flexibility to make seal widths between <NUM>,<NUM> and <NUM>, <NUM> (<NUM> and <NUM> inches) (or greater) on a single machine without requiring tooling changes. Thus, there is an ongoing need for a package sealing technology that effectively creates non-leaking seals of greater widths while reducing the overall area of the seal to provide materials saving and cost savings. State of the art sonotrodes are for example disclosed in <CIT>, <CIT> and <CIT>.

The following provides a summary of certain exemplary embodiments of the present invention. This summary is not an extensive overview and is not intended to identify key or critical aspects or elements of the present invention or to delineate its scope.

In accordance with one aspect of the present invention, a first sonotrode is provided. This sonotrode includes a sealing face; a front quarter wavelength region adjacent to the sealing face, wherein the front quarter wavelength region has been modified to increase the gain of the sonotrode; and a rear quarter wavelength region adjacent to the front quarter wavelength region, wherein the rear quarter wavelength region has been modified to create a non-uniform amplitude profile across the length of the sealing face of the sonotrode.

In accordance with another aspect of the present invention, a second sonotrode is provided. This sonotrode includes an elongated sealing face; a front quarter wavelength region adjacent to the sealing face, wherein the front quarter wavelength region has been modified to increase the gain of the sonotrode; a rear quarter wavelength region adjacent to the front quarter wavelength region; wherein the rear quarter wavelength region has been modified to create a non-uniform amplitude profile across the length of the sealing face of the sonotrode; wherein the modification to the front quarter wavelength region includes reducing the mass of the front quarter wavelength region relative to the rear quarter wavelength region; and at least one tuning slot formed therein for further adjusting the amplitude profile of the sonotrode.

In yet another aspect of this invention, a third sonotrode is provided. This sonotrode includes an elongated sealing face; a front quarter wavelength region adjacent to the sealing face, wherein the front quarter wavelength region has been modified to increase the gain of the sonotrode; a rear quarter wavelength region adjacent to the front quarter wavelength region, wherein the rear quarter wavelength region has been modified to create a non-uniform amplitude profile across the length of the sealing face of the sonotrode; wherein the modification to the rear quarter wavelength region includes modifying the rear quarter wavelength region to include a non-uniform distribution of mass therein; wherein the modification to the front quarter wavelength region includes reducing the mass of the front quarter wavelength region relative to the rear quarter wavelength region and forming a step between the front quarter wavelength region and the rear quarter wavelength region; and a plurality of tuning slots formed therein for further adjusting the amplitude profile of the sonotrode.

Additional features and aspects of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the exemplary embodiments. As will be appreciated by the skilled artisan, further embodiments of the invention are possible without departing from the scope of the invention. Accordingly, the drawings and associated descriptions are to be regarded as illustrative and not restrictive in nature.

The accompanying drawings, which are incorporated into and form a part of the specification, schematically illustrate one or more exemplary embodiments of the invention and, together with the general description given above and detailed description given below, serve to explain the principles of the invention, and wherein:.

Exemplary embodiments of the present invention are now described with reference to the Figures. Reference numerals are used throughout the detailed description to refer to the various elements and structures. Although the following detailed description contains many specifics for the purposes of illustration, a person of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.

The present invention relates generally to systems, devices, and methods for sealing packages and the like, and more specifically to a modular device or apparatus for use in the ultrasonic sealing of packages, wherein seals of greater width (compared to prior art systems and devices) may be created while reducing the overall surface area of the seal and reducing gas leakage. When compared to thermal seals, ultrasonic seals meet or exceed the strength thereof and provide reduced gas leakage rates at significantly reduced seal sizes. Reducing seal size permits reduction of the overall package size, which results in the reduction of materials costs. Reducing the gas leak rate improves and extends the shelf life of perishable products. The present invention provides a modular ultrasonic bag sealing apparatus or device that may be used with various existing bag sealing systems and with newly designed bag sealing systems.

<FIG> provide illustrations of an ultrasonic sealing module in accordance with an exemplary embodiment of the present invention. This device is intended for use in mass-production environments, but may be used in other environments, and is capable of sealing of a broad range of film thicknesses and widths. The device or apparatus depicted in the Figures may be retrofitted to commonly-used thermal sealing reciprocal bag makers or may be incorporated into new bag maker builds. The present invention is intended for vertical or horizontal form fill seal equipment (VFFS or HFFS), but could be applied to or adapted for use with virtually any type of packaging equipment. The modular aspect of this invention allows it to be connected to the existing end seal mechanical motion system of a commercially available bag making system. Mechanical self-leveling features included in ultrasonic sealing module of this invention permit the module to be adjusted as necessary following installation. In exemplary embodiments, the invention utilizes commercial off the shelf ultrasonic components including a power supply, transducer, and booster. With reference to <FIG>, the ultrasonic sealing module includes a sonotrode, uniquely designed anvil, and mechanical support system. The sonotrode is designed to provide reduced amplitude in the center of the sealing face region of the sonotrode, which is significantly different from the common ultrasonic practice of using a sonotrode with uniform amplitude across the width of the sealing face. The ultrasonic sonotrode can be over <NUM>,<NUM> (<NUM> inches) wide and is energized by a single ultrasonic transducer, which facilitates sealing packages of various sizes without requiring a tooling change. Much wider seams can be created with this invention as compared to prior art systems and devices.

Again with reference to the Figures, <FIG> provide various alternate views of exemplary ultrasonic sealing module <NUM>, which includes first sealing member or "front jaw" <NUM> and a second sealing member or "rear jaw" <NUM>; front mounting plate <NUM>; rear mounting plate <NUM>; first guide shaft <NUM>; and second guide shaft <NUM>. <FIG> provide alternate views of exemplary ultrasonic horn or sonotrode <NUM>, which includes leading edge or sealing face <NUM>; front ¼ wavelength region <NUM>; tuning slots <NUM>; rear ¼ wavelength region <NUM>; outer edges <NUM> of rear ¼ wavelength region <NUM>; first modified area <NUM> of rear ¼ wavelength region <NUM>; and second modified area <NUM> of rear ¼ wavelength region <NUM>. Sonotrode <NUM> is secured within mounting frame <NUM>, upon which stack mount <NUM> and ultrasonic transducer <NUM> are also mounted. Ultrasonic transducer <NUM> provides a predetermined amount of ultrasonic energy to sonotrode <NUM> when ultrasonic sealing module <NUM> is in operation. Rear jaw <NUM> includes anvil <NUM>, which is mounted on frame <NUM>, which in turn is slidably mounted on first guide shaft <NUM> and second guide shaft <NUM>. Sonotrode <NUM> is disposed within front jaw <NUM>, which cooperates with anvil <NUM> on rear jaw <NUM> to seal packages when ultrasonic sealing module <NUM> is in operation.

As shown in <FIG>, horn or sonotrode <NUM>, which may be manufactured from high-strength aluminum alloys, titanium, or other suitable materials, has been modified to provide a variable or non-uniform amplitude profile across sealing face <NUM>. <FIG> is an end view of sonotrode <NUM> showing the direction of the amplitude of vibration <NUM> through the front ¼ wavelength of sonotrode <NUM> and the rear ¼ wavelength of sonotrode <NUM>. With regard to the general design of sonotrode <NUM>, front ¼ wavelength region <NUM> includes a significant mass reduction (or step configuration) for increasing the gain of sonotrode <NUM> and rear ¼ wavelength region <NUM> has been modified to include discrete areas of varying thicknesses As illustrated by the exemplary embodiment shown in <FIG>, rear ¼ wavelength region <NUM> includes left and right outer edges <NUM> of rear ¼ wavelength <NUM>; left and right first modified regions <NUM> of rear ¼ wavelength <NUM>; and second modified area <NUM> of rear ¼ wavelength region <NUM>. The decreasing and/or variable thickness and height of these areas creates the non-uniform amplitude profile shown as line B in <FIG>, as opposed to the uniform amplitude profile shown as line A in <FIG>. Tuning slots <NUM> permit further tuning of sonotode <NUM>, as desired or as necessary. The number of tuning slots <NUM>, as well as the length, width, and specific geometry of tuning slots <NUM> may be changed or modified as desired or as necessary. The exemplary configuration of sonotrode <NUM> shown in the Figures, results in the amplitude profile of the center portion of sealing face <NUM> being <NUM>-<NUM>% (for example) lower than the outer regions of sealing face <NUM>. Reducing or lowering the amplitude in the center of sealing face <NUM> permits the effective sealing of the back seal region of a package, which typically includes three layers of packaging material that form a seam. Because there are three layers present in the back seal region, this region inherently experiences a higher force per unit area, which is undesirable. Accordingly, the amplitude is lowered in the middle of the sonotrode of this invention to counter the effect of the higher force per unit area. In other embodiments of this invention, the non-uniform amplitude profile includes an amplitude that is greater in the center of the sealing face than at the outer edges thereof.

In an ultrasonic seal [force x amplitude = energy], therefore if forces are higher, the amplitude may be lowered to achieve a uniform energy input along the width of the sealed region. Also, if a back seal region is hot as a result of recent thermal sealing, less energy will be required to form an ultrasonic end seal over the back seal region. The sonotrode is hottest in the center of the sealing face due to thermal transfer in bulk material as opposed to thermal transfer into the air at the edges of the sonotrode and the center of the sealing face is where the back seal region typically resides. Essentially, the sonotrode of the present invention provides varying amplitudes across the face of sonotrode for effectively welding multiple (e.g., three) layers of thin film to one another to form a seal. Prior art sonotrodes which provide a uniform amplitude distribution across the sealing face thereof create overwelding in the back seal region of a package, which is an undesirable outcome that the present invention overcomes.

The modular ultrasonic package sealing device of this invention is capable of producing ultrasonic seals below <NUM>,<NUM> (<NUM> inches) in width and over <NUM>,<NUM> (<NUM> inches) in width with no required tooling changes. A change in package width or material thickness does not require a tool change. This invention can seal packages which include the thin films commonly used in the snack package industry as well as thicker films used to package consumer products or foods such as produce, poultry, or dairy. The ultrasonic seals created with this invention are smaller in size than thermal seals, which permits a reduction in the required amount of packaging material. The ultrasonic sealing process of this invention also provides an improvement in sealing through minimal snack product (e.g., chips, salt, grease, etc.), which reduces in process scrap at the factory, and prevents or reduces the likelihood of spoiled or bad product from reaching the consumer. The improved ability to seal through snack product also allows for a reduction in package headspace, which further reduces overall material use. The ultrasonic seals created with this invention have been tested in mass-production environments (e.g., millions of packages sealed) and proven to have a lower gas (e.g., oxygen) leak rate when compared to traditional thermal seals. A lower gas transfer rate results in a longer product shelf life.

Other advantages of the present invention include a modular mechanical structure that supports the ultrasonic jaws of the device. This aspect facilitates retrofitting an existing bag maker equipment or incorporation into new bag maker builds and provides a mechanical structure that attaches to existing bag maker motion system so no ancillary motors or other motion devices are required. This invention provides: (i) a system that can seal thin films at high volume production rates without damage to ultrasonic components; (ii) a dual force system (spring or pneumatic) that provides minor compensation for self-leveling; and (iii) mechanical alignment features that allow the sonotrode and anvil weld faces to be parallel to one another other. This arrangement permits the very fine adjustments involved in leveling the sonotrode and anvil sealing faces used for thin film sealing, across a wide sealing face.

A further advantage of the present invention is its usefulness in the packaging of products that include chocolate or similar substances. Current packaging systems and methodologies used with products of this nature utilize a "cold seal" approach, wherein a pressure sensitive adhesive, similar to rubber cement, is applied to the sealing surfaces of the package and then pressed together. Because the ultrasonic sealing technology used with the present invention does not generate high heat in the sealing area, it can be used to replace cold seals in product packages that contain chocolate, thereby significantly reducing the cost of the package. As with other applications of this invention, the seal area can also be reduced, thereby contributing to reduced packaging material and material costs.

Claim 1:
A sonotrode (<NUM>), comprising:
(a) a sealing face (<NUM>);
(b) a front quarter wavelength region (<NUM>) adjacent to the sealing face (<NUM>), wherein the front quarter wavelength region (<NUM>) has been modified to increase the gain of the sonotrode (<NUM>); and
(c) a rear quarter wavelength region (<NUM>) adjacent to the front quarter wavelength region (<NUM>), characterized in that the rear quarter wavelength region (<NUM>) comprises discrete areas of varying thickness configured to create a non-uniform amplitude profile across the length of the sealing face (<NUM>) of the sonotrode (<NUM>);
wherein the non-uniform amplitude profile includes a region of lower amplitude in the center of the sealing face (<NUM>) and regions of higher amplitude on the outer edges of the sealing face (<NUM>).